CWE - VIEW SLICE: CWE-868: Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version) (4.17)

CWE VIEW: Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)

View ID: 868

Vulnerability Mapping: PROHIBITED This CWE ID must not be used to map to real-world vulnerabilities
Type: Graph

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Objective

CWE entries in this view (graph) are fully or partially eliminated by following the SEI CERT C++ Coding Standard, as published in 2016. This view is no longer being actively maintained, since it statically represents the coding rules as they were in 2016.

Audience

Stakeholder	Description
Software Developers	By following the CERT C++ Secure Coding Standard, developers will be able to fully or partially prevent the weaknesses that are identified in this view. In addition, developers can use a CWE coverage graph to determine which weaknesses are not directly addressed by the standard, which will help identify and resolve remaining gaps in training, tool acquisition, or other approaches for reducing weaknesses.
Product Customers	If a software developer claims to be following the CERT C++ Secure Coding Standard, then customers can search for the weaknesses in this view in order to formulate independent evidence of that claim.
Educators	Educators can use this view in multiple ways. For example, if there is a focus on teaching weaknesses, the educator could link them to the relevant Secure Coding Standard.

Relationships

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The following graph shows the tree-like relationships between weaknesses that exist at different levels of abstraction. At the highest level, categories and pillars exist to group weaknesses. Categories (which are not technically weaknesses) are special CWE entries used to group weaknesses that share a common characteristic. Pillars are weaknesses that are described in the most abstract fashion. Below these top-level entries are weaknesses are varying levels of abstraction. Classes are still very abstract, typically independent of any specific language or technology. Base level weaknesses are used to present a more specific type of weakness. A variant is a weakness that is described at a very low level of detail, typically limited to a specific language or technology. A chain is a set of weaknesses that must be reachable consecutively in order to produce an exploitable vulnerability. While a composite is a set of weaknesses that must all be present simultaneously in order to produce an exploitable vulnerability.

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868 - Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)

Category - a CWE entry that contains a set of other entries that share a common characteristic. CERT C++ Secure Coding Section 01 - Preprocessor (PRE) - (869)

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 869 (CERT C++ Secure Coding Section 01 - Preprocessor (PRE))

Weaknesses in this category are related to rules in the Preprocessor (PRE) section of the CERT C++ Secure Coding Standard. Since not all rules map to specific weaknesses, this category may be incomplete.

Category - a CWE entry that contains a set of other entries that share a common characteristic. CERT C++ Secure Coding Section 02 - Declarations and Initialization (DCL) - (870)

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 870 (CERT C++ Secure Coding Section 02 - Declarations and Initialization (DCL))

Weaknesses in this category are related to rules in the Declarations and Initialization (DCL) section of the CERT C++ Secure Coding Standard. Since not all rules map to specific weaknesses, this category may be incomplete.

Category - a CWE entry that contains a set of other entries that share a common characteristic. CERT C++ Secure Coding Section 03 - Expressions (EXP) - (871)

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 871 (CERT C++ Secure Coding Section 03 - Expressions (EXP))

Weaknesses in this category are related to rules in the Expressions (EXP) section of the CERT C++ Secure Coding Standard. Since not all rules map to specific weaknesses, this category may be incomplete.

Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource. NULL Pointer Dereference - (476)

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 871 (CERT C++ Secure Coding Section 03 - Expressions (EXP)) > 476 (NULL Pointer Dereference)

The product dereferences a pointer that it expects to be valid but is NULL. NPD null deref NPE nil pointer dereference

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 871 (CERT C++ Secure Coding Section 03 - Expressions (EXP)) > 480 (Use of Incorrect Operator)

The product accidentally uses the wrong operator, which changes the logic in security-relevant ways.

Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource. Incorrect Short Circuit Evaluation - (768)

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 871 (CERT C++ Secure Coding Section 03 - Expressions (EXP)) > 768 (Incorrect Short Circuit Evaluation)

The product contains a conditional statement with multiple logical expressions in which one of the non-leading expressions may produce side effects. This may lead to an unexpected state in the program after the execution of the conditional, because short-circuiting logic may prevent the side effects from occurring.

Category - a CWE entry that contains a set of other entries that share a common characteristic. CERT C++ Secure Coding Section 04 - Integers (INT) - (872)

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 872 (CERT C++ Secure Coding Section 04 - Integers (INT))

Weaknesses in this category are related to rules in the Integers (INT) section of the CERT C++ Secure Coding Standard. Since not all rules map to specific weaknesses, this category may be incomplete.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 872 (CERT C++ Secure Coding Section 04 - Integers (INT)) > 129 (Improper Validation of Array Index)

The product uses untrusted input when calculating or using an array index, but the product does not validate or incorrectly validates the index to ensure the index references a valid position within the array. out-of-bounds array index index-out-of-range array index underflow

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 872 (CERT C++ Secure Coding Section 04 - Integers (INT)) > 190 (Integer Overflow or Wraparound)

The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number. Overflow Wraparound wrap, wrap-around, wrap around

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 872 (CERT C++ Secure Coding Section 04 - Integers (INT)) > 192 (Integer Coercion Error)

Integer coercion refers to a set of flaws pertaining to the type casting, extension, or truncation of primitive data types.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 872 (CERT C++ Secure Coding Section 04 - Integers (INT)) > 197 (Numeric Truncation Error)

Truncation errors occur when a primitive is cast to a primitive of a smaller size and data is lost in the conversion.

Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource. Improper Input Validation - (20)

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 872 (CERT C++ Secure Coding Section 04 - Integers (INT)) > 20 (Improper Input Validation)

The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 872 (CERT C++ Secure Coding Section 04 - Integers (INT)) > 369 (Divide By Zero)

The product divides a value by zero.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 872 (CERT C++ Secure Coding Section 04 - Integers (INT)) > 466 (Return of Pointer Value Outside of Expected Range)

A function can return a pointer to memory that is outside of the buffer that the pointer is expected to reference.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 872 (CERT C++ Secure Coding Section 04 - Integers (INT)) > 587 (Assignment of a Fixed Address to a Pointer)

The product sets a pointer to a specific address other than NULL or 0.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 872 (CERT C++ Secure Coding Section 04 - Integers (INT)) > 606 (Unchecked Input for Loop Condition)

The product does not properly check inputs that are used for loop conditions, potentially leading to a denial of service or other consequences because of excessive looping.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 872 (CERT C++ Secure Coding Section 04 - Integers (INT)) > 676 (Use of Potentially Dangerous Function)

The product invokes a potentially dangerous function that could introduce a vulnerability if it is used incorrectly, but the function can also be used safely.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 872 (CERT C++ Secure Coding Section 04 - Integers (INT)) > 681 (Incorrect Conversion between Numeric Types)

When converting from one data type to another, such as long to integer, data can be omitted or translated in a way that produces unexpected values. If the resulting values are used in a sensitive context, then dangerous behaviors may occur.

Pillar - a weakness that is the most abstract type of weakness and represents a theme for all class/base/variant weaknesses related to it. A Pillar is different from a Category as a Pillar is still technically a type of weakness that describes a mistake, while a Category represents a common characteristic used to group related things. Incorrect Calculation - (682)

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 872 (CERT C++ Secure Coding Section 04 - Integers (INT)) > 682 (Incorrect Calculation)

The product performs a calculation that generates incorrect or unintended results that are later used in security-critical decisions or resource management.

Category - a CWE entry that contains a set of other entries that share a common characteristic. CERT C++ Secure Coding Section 05 - Floating Point Arithmetic (FLP) - (873)

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 873 (CERT C++ Secure Coding Section 05 - Floating Point Arithmetic (FLP))

Weaknesses in this category are related to rules in the Floating Point Arithmetic (FLP) section of the CERT C++ Secure Coding Standard. Since not all rules map to specific weaknesses, this category may be incomplete.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 873 (CERT C++ Secure Coding Section 05 - Floating Point Arithmetic (FLP)) > 369 (Divide By Zero)

The product divides a value by zero.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 873 (CERT C++ Secure Coding Section 05 - Floating Point Arithmetic (FLP)) > 681 (Incorrect Conversion between Numeric Types)

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 873 (CERT C++ Secure Coding Section 05 - Floating Point Arithmetic (FLP)) > 682 (Incorrect Calculation)

The product performs a calculation that generates incorrect or unintended results that are later used in security-critical decisions or resource management.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 873 (CERT C++ Secure Coding Section 05 - Floating Point Arithmetic (FLP)) > 686 (Function Call With Incorrect Argument Type)

The product calls a function, procedure, or routine, but the caller specifies an argument that is the wrong data type, which may lead to resultant weaknesses.

Category - a CWE entry that contains a set of other entries that share a common characteristic. CERT C++ Secure Coding Section 06 - Arrays and the STL (ARR) - (874)

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 874 (CERT C++ Secure Coding Section 06 - Arrays and the STL (ARR))

Weaknesses in this category are related to rules in the Arrays and the STL (ARR) section of the CERT C++ Secure Coding Standard. Since not all rules map to specific weaknesses, this category may be incomplete.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 874 (CERT C++ Secure Coding Section 06 - Arrays and the STL (ARR)) > 119 (Improper Restriction of Operations within the Bounds of a Memory Buffer)

The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data. Buffer Overflow buffer overrun memory safety

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 874 (CERT C++ Secure Coding Section 06 - Arrays and the STL (ARR)) > 129 (Improper Validation of Array Index)

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 874 (CERT C++ Secure Coding Section 06 - Arrays and the STL (ARR)) > 467 (Use of sizeof() on a Pointer Type)

The code calls sizeof() on a pointer type, which can be an incorrect calculation if the programmer intended to determine the size of the data that is being pointed to.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 874 (CERT C++ Secure Coding Section 06 - Arrays and the STL (ARR)) > 469 (Use of Pointer Subtraction to Determine Size)

The product subtracts one pointer from another in order to determine size, but this calculation can be incorrect if the pointers do not exist in the same memory chunk.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 874 (CERT C++ Secure Coding Section 06 - Arrays and the STL (ARR)) > 665 (Improper Initialization)

The product does not initialize or incorrectly initializes a resource, which might leave the resource in an unexpected state when it is accessed or used.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 874 (CERT C++ Secure Coding Section 06 - Arrays and the STL (ARR)) > 805 (Buffer Access with Incorrect Length Value)

The product uses a sequential operation to read or write a buffer, but it uses an incorrect length value that causes it to access memory that is outside of the bounds of the buffer.

Category - a CWE entry that contains a set of other entries that share a common characteristic. CERT C++ Secure Coding Section 07 - Characters and Strings (STR) - (875)

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 875 (CERT C++ Secure Coding Section 07 - Characters and Strings (STR))

Weaknesses in this category are related to rules in the Characters and Strings (STR) section of the CERT C++ Secure Coding Standard. Since not all rules map to specific weaknesses, this category may be incomplete.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 875 (CERT C++ Secure Coding Section 07 - Characters and Strings (STR)) > 119 (Improper Restriction of Operations within the Bounds of a Memory Buffer)

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 875 (CERT C++ Secure Coding Section 07 - Characters and Strings (STR)) > 120 (Buffer Copy without Checking Size of Input ('Classic Buffer Overflow'))

The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer, leading to a buffer overflow. Classic Buffer Overflow Unbounded Transfer

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 875 (CERT C++ Secure Coding Section 07 - Characters and Strings (STR)) > 170 (Improper Null Termination)

The product does not terminate or incorrectly terminates a string or array with a null character or equivalent terminator.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 875 (CERT C++ Secure Coding Section 07 - Characters and Strings (STR)) > 193 (Off-by-one Error)

A product calculates or uses an incorrect maximum or minimum value that is 1 more, or 1 less, than the correct value. off-by-five

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 875 (CERT C++ Secure Coding Section 07 - Characters and Strings (STR)) > 464 (Addition of Data Structure Sentinel)

The accidental addition of a data-structure sentinel can cause serious programming logic problems.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 875 (CERT C++ Secure Coding Section 07 - Characters and Strings (STR)) > 686 (Function Call With Incorrect Argument Type)

The product calls a function, procedure, or routine, but the caller specifies an argument that is the wrong data type, which may lead to resultant weaknesses.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 875 (CERT C++ Secure Coding Section 07 - Characters and Strings (STR)) > 704 (Incorrect Type Conversion or Cast)

The product does not correctly convert an object, resource, or structure from one type to a different type.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 875 (CERT C++ Secure Coding Section 07 - Characters and Strings (STR)) > 78 (Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection'))

The product constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command when it is sent to a downstream component. Shell injection Shell metacharacters OS Command Injection

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 875 (CERT C++ Secure Coding Section 07 - Characters and Strings (STR)) > 88 (Improper Neutralization of Argument Delimiters in a Command ('Argument Injection'))

The product constructs a string for a command to be executed by a separate component in another control sphere, but it does not properly delimit the intended arguments, options, or switches within that command string.

Category - a CWE entry that contains a set of other entries that share a common characteristic. CERT C++ Secure Coding Section 08 - Memory Management (MEM) - (876)

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 876 (CERT C++ Secure Coding Section 08 - Memory Management (MEM))

Weaknesses in this category are related to rules in the Memory Management (MEM) section of the CERT C++ Secure Coding Standard. Since not all rules map to specific weaknesses, this category may be incomplete.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 876 (CERT C++ Secure Coding Section 08 - Memory Management (MEM)) > 119 (Improper Restriction of Operations within the Bounds of a Memory Buffer)

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 876 (CERT C++ Secure Coding Section 08 - Memory Management (MEM)) > 128 (Wrap-around Error)

Wrap around errors occur whenever a value is incremented past the maximum value for its type and therefore "wraps around" to a very small, negative, or undefined value.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 876 (CERT C++ Secure Coding Section 08 - Memory Management (MEM)) > 131 (Incorrect Calculation of Buffer Size)

The product does not correctly calculate the size to be used when allocating a buffer, which could lead to a buffer overflow.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 876 (CERT C++ Secure Coding Section 08 - Memory Management (MEM)) > 190 (Integer Overflow or Wraparound)

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 876 (CERT C++ Secure Coding Section 08 - Memory Management (MEM)) > 20 (Improper Input Validation)

The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 876 (CERT C++ Secure Coding Section 08 - Memory Management (MEM)) > 226 (Sensitive Information in Resource Not Removed Before Reuse)

The product releases a resource such as memory or a file so that it can be made available for reuse, but it does not clear or "zeroize" the information contained in the resource before the product performs a critical state transition or makes the resource available for reuse by other entities.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 876 (CERT C++ Secure Coding Section 08 - Memory Management (MEM)) > 244 (Improper Clearing of Heap Memory Before Release ('Heap Inspection'))

Using realloc() to resize buffers that store sensitive information can leave the sensitive information exposed to attack, because it is not removed from memory.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 876 (CERT C++ Secure Coding Section 08 - Memory Management (MEM)) > 252 (Unchecked Return Value)

The product does not check the return value from a method or function, which can prevent it from detecting unexpected states and conditions.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 876 (CERT C++ Secure Coding Section 08 - Memory Management (MEM)) > 391 (Unchecked Error Condition)

[PLANNED FOR DEPRECATION. SEE MAINTENANCE NOTES AND CONSIDER CWE-252, CWE-248, OR CWE-1069.] Ignoring exceptions and other error conditions may allow an attacker to induce unexpected behavior unnoticed.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 876 (CERT C++ Secure Coding Section 08 - Memory Management (MEM)) > 404 (Improper Resource Shutdown or Release)

The product does not release or incorrectly releases a resource before it is made available for re-use.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 876 (CERT C++ Secure Coding Section 08 - Memory Management (MEM)) > 415 (Double Free)

The product calls free() twice on the same memory address. Double-free

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 876 (CERT C++ Secure Coding Section 08 - Memory Management (MEM)) > 416 (Use After Free)

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer. Dangling pointer UAF Use-After-Free

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 876 (CERT C++ Secure Coding Section 08 - Memory Management (MEM)) > 476 (NULL Pointer Dereference)

The product dereferences a pointer that it expects to be valid but is NULL. NPD null deref NPE nil pointer dereference

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 876 (CERT C++ Secure Coding Section 08 - Memory Management (MEM)) > 528 (Exposure of Core Dump File to an Unauthorized Control Sphere)

The product generates a core dump file in a directory, archive, or other resource that is stored, transferred, or otherwise made accessible to unauthorized actors.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 876 (CERT C++ Secure Coding Section 08 - Memory Management (MEM)) > 590 (Free of Memory not on the Heap)

The product calls free() on a pointer to memory that was not allocated using associated heap allocation functions such as malloc(), calloc(), or realloc().

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 876 (CERT C++ Secure Coding Section 08 - Memory Management (MEM)) > 591 (Sensitive Data Storage in Improperly Locked Memory)

The product stores sensitive data in memory that is not locked, or that has been incorrectly locked, which might cause the memory to be written to swap files on disk by the virtual memory manager. This can make the data more accessible to external actors.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 876 (CERT C++ Secure Coding Section 08 - Memory Management (MEM)) > 665 (Improper Initialization)

The product does not initialize or incorrectly initializes a resource, which might leave the resource in an unexpected state when it is accessed or used.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 876 (CERT C++ Secure Coding Section 08 - Memory Management (MEM)) > 687 (Function Call With Incorrectly Specified Argument Value)

The product calls a function, procedure, or routine, but the caller specifies an argument that contains the wrong value, which may lead to resultant weaknesses.

Chain - a Compound Element that is a sequence of two or more separate weaknesses that can be closely linked together within software. One weakness, X, can directly create the conditions that are necessary to cause another weakness, Y, to enter a vulnerable condition. When this happens, CWE refers to X as "primary" to Y, and Y is "resultant" from X. Chains can involve more than two weaknesses, and in some cases, they might have a tree-like structure. Unchecked Return Value to NULL Pointer Dereference - (690)

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 876 (CERT C++ Secure Coding Section 08 - Memory Management (MEM)) > 690 (Unchecked Return Value to NULL Pointer Dereference)

The product does not check for an error after calling a function that can return with a NULL pointer if the function fails, which leads to a resultant NULL pointer dereference.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 876 (CERT C++ Secure Coding Section 08 - Memory Management (MEM)) > 703 (Improper Check or Handling of Exceptional Conditions)

The product does not properly anticipate or handle exceptional conditions that rarely occur during normal operation of the product.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 876 (CERT C++ Secure Coding Section 08 - Memory Management (MEM)) > 754 (Improper Check for Unusual or Exceptional Conditions)

The product does not check or incorrectly checks for unusual or exceptional conditions that are not expected to occur frequently during day to day operation of the product.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 876 (CERT C++ Secure Coding Section 08 - Memory Management (MEM)) > 762 (Mismatched Memory Management Routines)

The product attempts to return a memory resource to the system, but it calls a release function that is not compatible with the function that was originally used to allocate that resource.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 876 (CERT C++ Secure Coding Section 08 - Memory Management (MEM)) > 770 (Allocation of Resources Without Limits or Throttling)

The product allocates a reusable resource or group of resources on behalf of an actor without imposing any restrictions on the size or number of resources that can be allocated, in violation of the intended security policy for that actor.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 876 (CERT C++ Secure Coding Section 08 - Memory Management (MEM)) > 822 (Untrusted Pointer Dereference)

The product obtains a value from an untrusted source, converts this value to a pointer, and dereferences the resulting pointer.

Category - a CWE entry that contains a set of other entries that share a common characteristic. CERT C++ Secure Coding Section 09 - Input Output (FIO) - (877)

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 877 (CERT C++ Secure Coding Section 09 - Input Output (FIO))

Weaknesses in this category are related to rules in the Input Output (FIO) section of the CERT C++ Secure Coding Standard. Since not all rules map to specific weaknesses, this category may be incomplete.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 877 (CERT C++ Secure Coding Section 09 - Input Output (FIO)) > 119 (Improper Restriction of Operations within the Bounds of a Memory Buffer)

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 877 (CERT C++ Secure Coding Section 09 - Input Output (FIO)) > 134 (Use of Externally-Controlled Format String)

The product uses a function that accepts a format string as an argument, but the format string originates from an external source.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 877 (CERT C++ Secure Coding Section 09 - Input Output (FIO)) > 22 (Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal'))

The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory. Directory traversal Path traversal

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 877 (CERT C++ Secure Coding Section 09 - Input Output (FIO)) > 241 (Improper Handling of Unexpected Data Type)

The product does not handle or incorrectly handles when a particular element is not the expected type, e.g. it expects a digit (0-9) but is provided with a letter (A-Z).

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 877 (CERT C++ Secure Coding Section 09 - Input Output (FIO)) > 276 (Incorrect Default Permissions)

During installation, installed file permissions are set to allow anyone to modify those files.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 877 (CERT C++ Secure Coding Section 09 - Input Output (FIO)) > 279 (Incorrect Execution-Assigned Permissions)

While it is executing, the product sets the permissions of an object in a way that violates the intended permissions that have been specified by the user.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 877 (CERT C++ Secure Coding Section 09 - Input Output (FIO)) > 362 (Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition'))

The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently. Race Condition

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 877 (CERT C++ Secure Coding Section 09 - Input Output (FIO)) > 367 (Time-of-check Time-of-use (TOCTOU) Race Condition)

The product checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check. This can cause the product to perform invalid actions when the resource is in an unexpected state. TOCTTOU TOCCTOU

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 877 (CERT C++ Secure Coding Section 09 - Input Output (FIO)) > 37 (Path Traversal: '/absolute/pathname/here')

The product accepts input in the form of a slash absolute path ('/absolute/pathname/here') without appropriate validation, which can allow an attacker to traverse the file system to unintended locations or access arbitrary files.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 877 (CERT C++ Secure Coding Section 09 - Input Output (FIO)) > 379 (Creation of Temporary File in Directory with Insecure Permissions)

The product creates a temporary file in a directory whose permissions allow unintended actors to determine the file's existence or otherwise access that file.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 877 (CERT C++ Secure Coding Section 09 - Input Output (FIO)) > 38 (Path Traversal: '\absolute\pathname\here')

The product accepts input in the form of a backslash absolute path ('\absolute\pathname\here') without appropriate validation, which can allow an attacker to traverse the file system to unintended locations or access arbitrary files.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 877 (CERT C++ Secure Coding Section 09 - Input Output (FIO)) > 39 (Path Traversal: 'C:dirname')

The product accepts input that contains a drive letter or Windows volume letter ('C:dirname') that potentially redirects access to an unintended location or arbitrary file.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 877 (CERT C++ Secure Coding Section 09 - Input Output (FIO)) > 391 (Unchecked Error Condition)

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 877 (CERT C++ Secure Coding Section 09 - Input Output (FIO)) > 403 (Exposure of File Descriptor to Unintended Control Sphere ('File Descriptor Leak'))

A process does not close sensitive file descriptors before invoking a child process, which allows the child to perform unauthorized I/O operations using those descriptors. File descriptor leak

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 877 (CERT C++ Secure Coding Section 09 - Input Output (FIO)) > 404 (Improper Resource Shutdown or Release)

The product does not release or incorrectly releases a resource before it is made available for re-use.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 877 (CERT C++ Secure Coding Section 09 - Input Output (FIO)) > 41 (Improper Resolution of Path Equivalence)

The product is vulnerable to file system contents disclosure through path equivalence. Path equivalence involves the use of special characters in file and directory names. The associated manipulations are intended to generate multiple names for the same object.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 877 (CERT C++ Secure Coding Section 09 - Input Output (FIO)) > 552 (Files or Directories Accessible to External Parties)

The product makes files or directories accessible to unauthorized actors, even though they should not be.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 877 (CERT C++ Secure Coding Section 09 - Input Output (FIO)) > 59 (Improper Link Resolution Before File Access ('Link Following'))

The product attempts to access a file based on the filename, but it does not properly prevent that filename from identifying a link or shortcut that resolves to an unintended resource. insecure temporary file Zip Slip

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 877 (CERT C++ Secure Coding Section 09 - Input Output (FIO)) > 62 (UNIX Hard Link)

The product, when opening a file or directory, does not sufficiently account for when the name is associated with a hard link to a target that is outside of the intended control sphere. This could allow an attacker to cause the product to operate on unauthorized files.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 877 (CERT C++ Secure Coding Section 09 - Input Output (FIO)) > 64 (Windows Shortcut Following (.LNK))

The product, when opening a file or directory, does not sufficiently handle when the file is a Windows shortcut (.LNK) whose target is outside of the intended control sphere. This could allow an attacker to cause the product to operate on unauthorized files. Windows symbolic link following symlink

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 877 (CERT C++ Secure Coding Section 09 - Input Output (FIO)) > 65 (Windows Hard Link)

The product, when opening a file or directory, does not sufficiently handle when the name is associated with a hard link to a target that is outside of the intended control sphere. This could allow an attacker to cause the product to operate on unauthorized files.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 877 (CERT C++ Secure Coding Section 09 - Input Output (FIO)) > 67 (Improper Handling of Windows Device Names)

The product constructs pathnames from user input, but it does not handle or incorrectly handles a pathname containing a Windows device name such as AUX or CON. This typically leads to denial of service or an information exposure when the application attempts to process the pathname as a regular file.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 877 (CERT C++ Secure Coding Section 09 - Input Output (FIO)) > 675 (Multiple Operations on Resource in Single-Operation Context)

The product performs the same operation on a resource two or more times, when the operation should only be applied once.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 877 (CERT C++ Secure Coding Section 09 - Input Output (FIO)) > 676 (Use of Potentially Dangerous Function)

The product invokes a potentially dangerous function that could introduce a vulnerability if it is used incorrectly, but the function can also be used safely.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 877 (CERT C++ Secure Coding Section 09 - Input Output (FIO)) > 73 (External Control of File Name or Path)

The product allows user input to control or influence paths or file names that are used in filesystem operations.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 877 (CERT C++ Secure Coding Section 09 - Input Output (FIO)) > 732 (Incorrect Permission Assignment for Critical Resource)

The product specifies permissions for a security-critical resource in a way that allows that resource to be read or modified by unintended actors.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 877 (CERT C++ Secure Coding Section 09 - Input Output (FIO)) > 770 (Allocation of Resources Without Limits or Throttling)

Category - a CWE entry that contains a set of other entries that share a common characteristic. CERT C++ Secure Coding Section 10 - Environment (ENV) - (878)

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 878 (CERT C++ Secure Coding Section 10 - Environment (ENV))

Weaknesses in this category are related to rules in the Environment (ENV) section of the CERT C++ Secure Coding Standard. Since not all rules map to specific weaknesses, this category may be incomplete.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 878 (CERT C++ Secure Coding Section 10 - Environment (ENV)) > 119 (Improper Restriction of Operations within the Bounds of a Memory Buffer)

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 878 (CERT C++ Secure Coding Section 10 - Environment (ENV)) > 426 (Untrusted Search Path)

The product searches for critical resources using an externally-supplied search path that can point to resources that are not under the product's direct control. Untrusted Path

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 878 (CERT C++ Secure Coding Section 10 - Environment (ENV)) > 462 (Duplicate Key in Associative List (Alist))

Duplicate keys in associative lists can lead to non-unique keys being mistaken for an error.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 878 (CERT C++ Secure Coding Section 10 - Environment (ENV)) > 705 (Incorrect Control Flow Scoping)

The product does not properly return control flow to the proper location after it has completed a task or detected an unusual condition.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 878 (CERT C++ Secure Coding Section 10 - Environment (ENV)) > 78 (Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection'))

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 878 (CERT C++ Secure Coding Section 10 - Environment (ENV)) > 807 (Reliance on Untrusted Inputs in a Security Decision)

The product uses a protection mechanism that relies on the existence or values of an input, but the input can be modified by an untrusted actor in a way that bypasses the protection mechanism.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 878 (CERT C++ Secure Coding Section 10 - Environment (ENV)) > 88 (Improper Neutralization of Argument Delimiters in a Command ('Argument Injection'))

Category - a CWE entry that contains a set of other entries that share a common characteristic. CERT C++ Secure Coding Section 11 - Signals (SIG) - (879)

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 879 (CERT C++ Secure Coding Section 11 - Signals (SIG))

Weaknesses in this category are related to rules in the Signals (SIG) section of the CERT C++ Secure Coding Standard. Since not all rules map to specific weaknesses, this category may be incomplete.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 879 (CERT C++ Secure Coding Section 11 - Signals (SIG)) > 479 (Signal Handler Use of a Non-reentrant Function)

The product defines a signal handler that calls a non-reentrant function.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 879 (CERT C++ Secure Coding Section 11 - Signals (SIG)) > 662 (Improper Synchronization)

The product utilizes multiple threads or processes to allow temporary access to a shared resource that can only be exclusive to one process at a time, but it does not properly synchronize these actions, which might cause simultaneous accesses of this resource by multiple threads or processes.

Category - a CWE entry that contains a set of other entries that share a common characteristic. CERT C++ Secure Coding Section 12 - Exceptions and Error Handling (ERR) - (880)

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 880 (CERT C++ Secure Coding Section 12 - Exceptions and Error Handling (ERR))

Weaknesses in this category are related to rules in the Exceptions and Error Handling (ERR) section of the CERT C++ Secure Coding Standard. Since not all rules map to specific weaknesses, this category may be incomplete.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 880 (CERT C++ Secure Coding Section 12 - Exceptions and Error Handling (ERR)) > 209 (Generation of Error Message Containing Sensitive Information)

The product generates an error message that includes sensitive information about its environment, users, or associated data.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 880 (CERT C++ Secure Coding Section 12 - Exceptions and Error Handling (ERR)) > 390 (Detection of Error Condition Without Action)

The product detects a specific error, but takes no actions to handle the error.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 880 (CERT C++ Secure Coding Section 12 - Exceptions and Error Handling (ERR)) > 391 (Unchecked Error Condition)

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 880 (CERT C++ Secure Coding Section 12 - Exceptions and Error Handling (ERR)) > 460 (Improper Cleanup on Thrown Exception)

The product does not clean up its state or incorrectly cleans up its state when an exception is thrown, leading to unexpected state or control flow.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 880 (CERT C++ Secure Coding Section 12 - Exceptions and Error Handling (ERR)) > 497 (Exposure of Sensitive System Information to an Unauthorized Control Sphere)

The product does not properly prevent sensitive system-level information from being accessed by unauthorized actors who do not have the same level of access to the underlying system as the product does.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 880 (CERT C++ Secure Coding Section 12 - Exceptions and Error Handling (ERR)) > 544 (Missing Standardized Error Handling Mechanism)

The product does not use a standardized method for handling errors throughout the code, which might introduce inconsistent error handling and resultant weaknesses.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 880 (CERT C++ Secure Coding Section 12 - Exceptions and Error Handling (ERR)) > 703 (Improper Check or Handling of Exceptional Conditions)

The product does not properly anticipate or handle exceptional conditions that rarely occur during normal operation of the product.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 880 (CERT C++ Secure Coding Section 12 - Exceptions and Error Handling (ERR)) > 705 (Incorrect Control Flow Scoping)

The product does not properly return control flow to the proper location after it has completed a task or detected an unusual condition.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 880 (CERT C++ Secure Coding Section 12 - Exceptions and Error Handling (ERR)) > 754 (Improper Check for Unusual or Exceptional Conditions)

The product does not check or incorrectly checks for unusual or exceptional conditions that are not expected to occur frequently during day to day operation of the product.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 880 (CERT C++ Secure Coding Section 12 - Exceptions and Error Handling (ERR)) > 755 (Improper Handling of Exceptional Conditions)

The product does not handle or incorrectly handles an exceptional condition.

Category - a CWE entry that contains a set of other entries that share a common characteristic. CERT C++ Secure Coding Section 13 - Object Oriented Programming (OOP) - (881)

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 881 (CERT C++ Secure Coding Section 13 - Object Oriented Programming (OOP))

Weaknesses in this category are related to rules in the Object Oriented Programming (OOP) section of the CERT C++ Secure Coding Standard. Since not all rules map to specific weaknesses, this category may be incomplete.

Category - a CWE entry that contains a set of other entries that share a common characteristic. CERT C++ Secure Coding Section 14 - Concurrency (CON) - (882)

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 882 (CERT C++ Secure Coding Section 14 - Concurrency (CON))

Weaknesses in this category are related to rules in the Concurrency (CON) section of the CERT C++ Secure Coding Standard. Since not all rules map to specific weaknesses, this category may be incomplete.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 882 (CERT C++ Secure Coding Section 14 - Concurrency (CON)) > 362 (Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition'))

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 882 (CERT C++ Secure Coding Section 14 - Concurrency (CON)) > 366 (Race Condition within a Thread)

If two threads of execution use a resource simultaneously, there exists the possibility that resources may be used while invalid, in turn making the state of execution undefined.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 882 (CERT C++ Secure Coding Section 14 - Concurrency (CON)) > 404 (Improper Resource Shutdown or Release)

The product does not release or incorrectly releases a resource before it is made available for re-use.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 882 (CERT C++ Secure Coding Section 14 - Concurrency (CON)) > 488 (Exposure of Data Element to Wrong Session)

The product does not sufficiently enforce boundaries between the states of different sessions, causing data to be provided to, or used by, the wrong session.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 882 (CERT C++ Secure Coding Section 14 - Concurrency (CON)) > 772 (Missing Release of Resource after Effective Lifetime)

The product does not release a resource after its effective lifetime has ended, i.e., after the resource is no longer needed.

Category - a CWE entry that contains a set of other entries that share a common characteristic. CERT C++ Secure Coding Section 49 - Miscellaneous (MSC) - (883)

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 883 (CERT C++ Secure Coding Section 49 - Miscellaneous (MSC))

Weaknesses in this category are related to rules in the Miscellaneous (MSC) section of the CERT C++ Secure Coding Standard. Since not all rules map to specific weaknesses, this category may be incomplete.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 883 (CERT C++ Secure Coding Section 49 - Miscellaneous (MSC)) > 116 (Improper Encoding or Escaping of Output)

The product prepares a structured message for communication with another component, but encoding or escaping of the data is either missing or done incorrectly. As a result, the intended structure of the message is not preserved. Output Sanitization Output Validation Output Encoding

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 883 (CERT C++ Secure Coding Section 49 - Miscellaneous (MSC)) > 14 (Compiler Removal of Code to Clear Buffers)

Sensitive memory is cleared according to the source code, but compiler optimizations leave the memory untouched when it is not read from again, aka "dead store removal."

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 883 (CERT C++ Secure Coding Section 49 - Miscellaneous (MSC)) > 176 (Improper Handling of Unicode Encoding)

The product does not properly handle when an input contains Unicode encoding.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 883 (CERT C++ Secure Coding Section 49 - Miscellaneous (MSC)) > 20 (Improper Input Validation)

The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 883 (CERT C++ Secure Coding Section 49 - Miscellaneous (MSC)) > 327 (Use of a Broken or Risky Cryptographic Algorithm)

The product uses a broken or risky cryptographic algorithm or protocol.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 883 (CERT C++ Secure Coding Section 49 - Miscellaneous (MSC)) > 330 (Use of Insufficiently Random Values)

The product uses insufficiently random numbers or values in a security context that depends on unpredictable numbers.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 883 (CERT C++ Secure Coding Section 49 - Miscellaneous (MSC)) > 480 (Use of Incorrect Operator)

The product accidentally uses the wrong operator, which changes the logic in security-relevant ways.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 883 (CERT C++ Secure Coding Section 49 - Miscellaneous (MSC)) > 482 (Comparing instead of Assigning)

The code uses an operator for comparison when the intention was to perform an assignment.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 883 (CERT C++ Secure Coding Section 49 - Miscellaneous (MSC)) > 561 (Dead Code)

The product contains dead code, which can never be executed.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 883 (CERT C++ Secure Coding Section 49 - Miscellaneous (MSC)) > 563 (Assignment to Variable without Use)

The variable's value is assigned but never used, making it a dead store. Unused Variable

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 883 (CERT C++ Secure Coding Section 49 - Miscellaneous (MSC)) > 570 (Expression is Always False)

The product contains an expression that will always evaluate to false.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 883 (CERT C++ Secure Coding Section 49 - Miscellaneous (MSC)) > 571 (Expression is Always True)

The product contains an expression that will always evaluate to true.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 883 (CERT C++ Secure Coding Section 49 - Miscellaneous (MSC)) > 697 (Incorrect Comparison)

The product compares two entities in a security-relevant context, but the comparison is incorrect, which may lead to resultant weaknesses.

868 (Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)) > 883 (CERT C++ Secure Coding Section 49 - Miscellaneous (MSC)) > 704 (Incorrect Type Conversion or Cast)

The product does not correctly convert an object, resource, or structure from one type to a different type.

Vulnerability Mapping Notes

Usage: PROHIBITED

(this CWE ID must not be used to map to real-world vulnerabilities)

Reason: View

Rationale:

This entry is a View. Views are not weaknesses and therefore inappropriate to describe the root causes of vulnerabilities.

Comments:

Use this View or other Views to search and navigate for the appropriate weakness.

Notes

Relationship

The relationships in this view were determined based on specific statements within the rules from the standard. Not all rules have direct relationships to individual weaknesses, although they likely have chaining relationships in specific circumstances.

References

[REF-847] The Software Engineering Institute. "SEI CERT C++ Coding Standard". <https://wiki.sei.cmu.edu/confluence/pages/viewpage.action?pageId=88046682>.

View Metrics

	CWEs in this view		Total CWEs
Weaknesses	95	out of	943
Categories	15	out of	374
Views	0	out of	51
Total	110	out of	1368

Content History

Submissions
Submission Date	Submitter	Organization
2011-08-04 (CWE 2.1, 2011-09-13)	CWE Content Team	MITRE
2011-08-04 (CWE 2.1, 2011-09-13)
Modifications
Modification Date	Modifier	Organization
2019-01-03	CWE Content Team	MITRE
2019-01-03	updated Description, Maintenance_Notes, Name, References
2020-02-24	CWE Content Team	MITRE
2020-02-24	updated View_Audience
2021-03-15	CWE Content Team	MITRE
2021-03-15	updated Description, Maintenance_Notes
2023-06-29	CWE Content Team	MITRE
2023-06-29	updated Mapping_Notes
Previous Entry Names
Change Date	Previous Entry Name
2019-01-03	Weaknesses Addressed by the CERT C++ Secure Coding Standard

View Components

Weakness ID: 770

Vulnerability Mapping: ALLOWED This CWE ID may be used to map to real-world vulnerabilities
Abstraction: Base Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.

View customized information:

For users who are interested in more notional aspects of a weakness. Example: educators, technical writers, and project/program managers. For users who are concerned with the practical application and details about the nature of a weakness and how to prevent it from happening. Example: tool developers, security researchers, pen-testers, incident response analysts. For users who are mapping an issue to CWE/CAPEC IDs, i.e., finding the most appropriate CWE for a specific issue (e.g., a CVE record). Example: tool developers, security researchers. For users who wish to see all available information for the CWE/CAPEC entry. For users who want to customize what details are displayed.

Description

Extended Description

Code frequently has to work with limited resources, so programmers must be careful to ensure that resources are not consumed too quickly, or too easily. Without use of quotas, resource limits, or other protection mechanisms, it can be easy for an attacker to consume many resources by rapidly making many requests, or causing larger resources to be used than is needed. When too many resources are allocated, or if a single resource is too large, then it can prevent the code from working correctly, possibly leading to a denial of service.

Common Consequences

This table specifies different individual consequences associated with the weakness. The Scope identifies the application security area that is violated, while the Impact describes the negative technical impact that arises if an adversary succeeds in exploiting this weakness. The Likelihood provides information about how likely the specific consequence is expected to be seen relative to the other consequences in the list. For example, there may be high likelihood that a weakness will be exploited to achieve a certain impact, but a low likelihood that it will be exploited to achieve a different impact.

Impact	Details
DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory); DoS: Resource Consumption (Other)	Scope: Availability When allocating resources without limits, an attacker could prevent other systems, applications, or processes from accessing the same type of resource.

Potential Mitigations

Phase(s)	Mitigation
Requirements	Clearly specify the minimum and maximum expectations for capabilities, and dictate which behaviors are acceptable when resource allocation reaches limits.
Architecture and Design	Limit the amount of resources that are accessible to unprivileged users. Set per-user limits for resources. Allow the system administrator to define these limits. Be careful to avoid CWE-410.
Architecture and Design	Design throttling mechanisms into the system architecture. The best protection is to limit the amount of resources that an unauthorized user can cause to be expended. A strong authentication and access control model will help prevent such attacks from occurring in the first place, and it will help the administrator to identify who is committing the abuse. The login application should be protected against DoS attacks as much as possible. Limiting the database access, perhaps by caching result sets, can help minimize the resources expended. To further limit the potential for a DoS attack, consider tracking the rate of requests received from users and blocking requests that exceed a defined rate threshold.
Implementation	Strategy: Input Validation Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does. When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue." Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright. Note: This will only be applicable to cases where user input can influence the size or frequency of resource allocations.
Architecture and Design	For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.
Architecture and Design	Mitigation of resource exhaustion attacks requires that the target system either: recognizes the attack and denies that user further access for a given amount of time, typically by using increasing time delays uniformly throttles all requests in order to make it more difficult to consume resources more quickly than they can again be freed. The first of these solutions is an issue in itself though, since it may allow attackers to prevent the use of the system by a particular valid user. If the attacker impersonates the valid user, they may be able to prevent the user from accessing the server in question. The second solution can be difficult to effectively institute -- and even when properly done, it does not provide a full solution. It simply requires more resources on the part of the attacker.
Architecture and Design	Ensure that protocols have specific limits of scale placed on them.
Architecture and Design; Implementation	If the program must fail, ensure that it fails gracefully (fails closed). There may be a temptation to simply let the program fail poorly in cases such as low memory conditions, but an attacker may be able to assert control before the software has fully exited. Alternately, an uncontrolled failure could cause cascading problems with other downstream components; for example, the program could send a signal to a downstream process so the process immediately knows that a problem has occurred and has a better chance of recovery. Ensure that all failures in resource allocation place the system into a safe posture.
Operation; Architecture and Design	Strategy: Resource Limitation Use resource-limiting settings provided by the operating system or environment. For example, when managing system resources in POSIX, setrlimit() can be used to set limits for certain types of resources, and getrlimit() can determine how many resources are available. However, these functions are not available on all operating systems. When the current levels get close to the maximum that is defined for the application (see CWE-770), then limit the allocation of further resources to privileged users; alternately, begin releasing resources for less-privileged users. While this mitigation may protect the system from attack, it will not necessarily stop attackers from adversely impacting other users. Ensure that the application performs the appropriate error checks and error handling in case resources become unavailable (CWE-703).

Relationships

This table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.

Relevant to the view "Research Concepts" (View-1000)

Nature	Type	ID	Name
ChildOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	400	Uncontrolled Resource Consumption
ChildOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	665	Improper Initialization
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	774	Allocation of File Descriptors or Handles Without Limits or Throttling
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	789	Memory Allocation with Excessive Size Value
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	1325	Improperly Controlled Sequential Memory Allocation
CanFollow	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	20	Improper Input Validation

Relevant to the view "Software Development" (View-699)

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	399	Resource Management Errors
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	840	Business Logic Errors

Relevant to the view "Weaknesses for Simplified Mapping of Published Vulnerabilities" (View-1003)

Nature	Type	ID	Name
ChildOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	400	Uncontrolled Resource Consumption

Relevant to the view "Architectural Concepts" (View-1008)

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1011	Authorize Actors

Modes Of Introduction

The different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the life cycle at which introduction may occur, while the Note provides a typical scenario related to introduction during the given phase.

Phase	Note
Architecture and Design	OMISSION: This weakness is caused by missing a security tactic during the architecture and design phase.
Implementation
Operation
System Configuration

Applicable Platforms

This listing shows possible areas for which the given weakness could appear. These may be for specific named Languages, Operating Systems, Architectures, Paradigms, Technologies, or a class of such platforms. The platform is listed along with how frequently the given weakness appears for that instance.

Languages

Class: Not Language-Specific (Often Prevalent)

Likelihood Of Exploit

High

Demonstrative Examples

Example 1

This code allocates a socket and forks each time it receives a new connection.

(bad code)

Example Language: C

sock=socket(AF_INET, SOCK_STREAM, 0);
while (1) {

newsock=accept(sock, ...);
printf("A connection has been accepted\n");
pid = fork();

}

The program does not track how many connections have been made, and it does not limit the number of connections. Because forking is a relatively expensive operation, an attacker would be able to cause the system to run out of CPU, processes, or memory by making a large number of connections. Alternatively, an attacker could consume all available connections, preventing others from accessing the system remotely.

Example 2

In the following example a server socket connection is used to accept a request to store data on the local file system using a specified filename. The method openSocketConnection establishes a server socket to accept requests from a client. When a client establishes a connection to this service the getNextMessage method is first used to retrieve from the socket the name of the file to store the data, the openFileToWrite method will validate the filename and open a file to write to on the local file system. The getNextMessage is then used within a while loop to continuously read data from the socket and output the data to the file until there is no longer any data from the socket.

(bad code)

Example Language: C

int writeDataFromSocketToFile(char *host, int port)
{

char filename[FILENAME_SIZE];
char buffer[BUFFER_SIZE];
int socket = openSocketConnection(host, port);

if (socket < 0) {

printf("Unable to open socket connection");
return(FAIL);

}
if (getNextMessage(socket, filename, FILENAME_SIZE) > 0) {

if (openFileToWrite(filename) > 0) {

while (getNextMessage(socket, buffer, BUFFER_SIZE) > 0){

if (!(writeToFile(buffer) > 0))

break;

}

}
closeFile();

}
closeSocket(socket);

}

This example creates a situation where data can be dumped to a file on the local file system without any limits on the size of the file. This could potentially exhaust file or disk resources and/or limit other clients' ability to access the service.

Example 3

In the following example, the processMessage method receives a two dimensional character array containing the message to be processed. The two-dimensional character array contains the length of the message in the first character array and the message body in the second character array. The getMessageLength method retrieves the integer value of the length from the first character array. After validating that the message length is greater than zero, the body character array pointer points to the start of the second character array of the two-dimensional character array and memory is allocated for the new body character array.

(bad code)

Example Language: C

/* process message accepts a two-dimensional character array of the form [length][body] containing the message to be processed */
int processMessage(char **message)
{

char *body;

int length = getMessageLength(message[0]);

if (length > 0) {

body = &message[1][0];
processMessageBody(body);
return(SUCCESS);

}
else {

printf("Unable to process message; invalid message length");
return(FAIL);

}

This example creates a situation where the length of the body character array can be very large and will consume excessive memory, exhausting system resources. This can be avoided by restricting the length of the second character array with a maximum length check

Also, consider changing the type from 'int' to 'unsigned int', so that you are always guaranteed that the number is positive. This might not be possible if the protocol specifically requires allowing negative values, or if you cannot control the return value from getMessageLength(), but it could simplify the check to ensure the input is positive, and eliminate other errors such as signed-to-unsigned conversion errors (CWE-195) that may occur elsewhere in the code.

(good code)

Example Language: C

unsigned int length = getMessageLength(message[0]);
if ((length > 0) && (length < MAX_LENGTH)) {...}

Example 4

In the following example, a server object creates a server socket and accepts client connections to the socket. For every client connection to the socket a separate thread object is generated using the ClientSocketThread class that handles request made by the client through the socket.

(bad code)

Example Language: Java

public void acceptConnections() {

try {

ServerSocket serverSocket = new ServerSocket(SERVER_PORT);
int counter = 0;
boolean hasConnections = true;
while (hasConnections) {

Socket client = serverSocket.accept();
Thread t = new Thread(new ClientSocketThread(client));
t.setName(client.getInetAddress().getHostName() + ":" + counter++);
t.start();

}
serverSocket.close();

} catch (IOException ex) {...}

}

In this example there is no limit to the number of client connections and client threads that are created. Allowing an unlimited number of client connections and threads could potentially overwhelm the system and system resources.

The server should limit the number of client connections and the client threads that are created. This can be easily done by creating a thread pool object that limits the number of threads that are generated.

(good code)

Example Language: Java

public static final int SERVER_PORT = 4444;
public static final int MAX_CONNECTIONS = 10;
...

public void acceptConnections() {

try {

ServerSocket serverSocket = new ServerSocket(SERVER_PORT);
int counter = 0;
boolean hasConnections = true;
while (hasConnections) {

hasConnections = checkForMoreConnections();
Socket client = serverSocket.accept();
Thread t = new Thread(new ClientSocketThread(client));
t.setName(client.getInetAddress().getHostName() + ":" + counter++);
ExecutorService pool = Executors.newFixedThreadPool(MAX_CONNECTIONS);
pool.execute(t);

}
serverSocket.close();

} catch (IOException ex) {...}

}

Example 5

An unnamed web site allowed a user to purchase tickets for an event. A menu option allowed the user to purchase up to 10 tickets, but the back end did not restrict the actual number of tickets that could be purchased.

Example 5 References:

[REF-667] Rafal Los. "Real-Life Example of a 'Business Logic Defect' (Screen Shots!)". 2011. <http://h30501.www3.hp.com/t5/Following-the-White-Rabbit-A/Real-Life-Example-of-a-Business-Logic-Defect-Screen-Shots/ba-p/22581>.

Example 6

Here the problem is that every time a connection is made, more memory is allocated. So if one just opened up more and more connections, eventually the machine would run out of memory.

(bad code)

Example Language: C

bar connection() {

foo = malloc(1024);
return foo;

}

endConnection(bar foo) {

free(foo);

}

int main() {

while(1) {

foo=connection();

}

endConnection(foo)

}

Selected Observed Examples

Note: this is a curated list of examples for users to understand the variety of ways in which this weakness can be introduced. It is not a complete list of all CVEs that are related to this CWE entry.

Reference	Description
CVE-2022-21668	Chain: Python library does not limit the resources used to process images that specify a very large number of bands (CWE-1284), leading to excessive memory consumption (CWE-789) or an integer overflow (CWE-190).
CVE-2009-4017	Language interpreter does not restrict the number of temporary files being created when handling a MIME request with a large number of parts..
CVE-2009-2726	Driver does not use a maximum width when invoking sscanf style functions, causing stack consumption.
CVE-2009-2540	Large integer value for a length property in an object causes a large amount of memory allocation.
CVE-2009-2054	Product allows exhaustion of file descriptors when processing a large number of TCP packets.
CVE-2008-5180	Communication product allows memory consumption with a large number of SIP requests, which cause many sessions to be created.
CVE-2008-1700	Product allows attackers to cause a denial of service via a large number of directives, each of which opens a separate window.
CVE-2005-4650	CMS does not restrict the number of searches that can occur simultaneously, leading to resource exhaustion.
CVE-2020-15100	web application scanner attempts to read an excessively large file created by a user, causing process termination
CVE-2020-7218	Go-based workload orchestrator does not limit resource usage with unauthenticated connections, allowing a DoS by flooding the service

Detection Methods

Method	Details
Manual Static Analysis	Manual static analysis can be useful for finding this weakness, but it might not achieve desired code coverage within limited time constraints. If denial-of-service is not considered a significant risk, or if there is strong emphasis on consequences such as code execution, then manual analysis may not focus on this weakness at all.
Fuzzing	While fuzzing is typically geared toward finding low-level implementation bugs, it can inadvertently find uncontrolled resource allocation problems. This can occur when the fuzzer generates a large number of test cases but does not restart the targeted product in between test cases. If an individual test case produces a crash, but it does not do so reliably, then an inability to limit resource allocation may be the cause. When the allocation is directly affected by numeric inputs, then fuzzing may produce indications of this weakness. Effectiveness: Opportunistic
Automated Dynamic Analysis	Certain automated dynamic analysis techniques may be effective in producing side effects of uncontrolled resource allocation problems, especially with resources such as processes, memory, and connections. The technique may involve generating a large number of requests to the product within a short time frame. Manual analysis is likely required to interpret the results.
Automated Static Analysis	Specialized configuration or tuning may be required to train automated tools to recognize this weakness. Automated static analysis typically has limited utility in recognizing unlimited allocation problems, except for the missing release of program-independent system resources such as files, sockets, and processes, or unchecked arguments to memory. For system resources, automated static analysis may be able to detect circumstances in which resources are not released after they have expired, or if too much of a resource is requested at once, as can occur with memory. Automated analysis of configuration files may be able to detect settings that do not specify a maximum value. Automated static analysis tools will not be appropriate for detecting exhaustion of custom resources, such as an intended security policy in which a bulletin board user is only allowed to make a limited number of posts per day.

Memberships

This MemberOf Relationships table shows additional CWE Categories and Views that reference this weakness as a member. This information is often useful in understanding where a weakness fits within the context of external information sources.

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	802	2010 Top 25 - Risky Resource Management
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	857	The CERT Oracle Secure Coding Standard for Java (2011) Chapter 14 - Input Output (FIO)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	858	The CERT Oracle Secure Coding Standard for Java (2011) Chapter 15 - Serialization (SER)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	861	The CERT Oracle Secure Coding Standard for Java (2011) Chapter 18 - Miscellaneous (MSC)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	867	2011 Top 25 - Weaknesses On the Cusp
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	876	CERT C++ Secure Coding Section 08 - Memory Management (MEM)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	877	CERT C++ Secure Coding Section 09 - Input Output (FIO)
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	884	CWE Cross-section
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	985	SFP Secondary Cluster: Unrestricted Consumption
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1147	SEI CERT Oracle Secure Coding Standard for Java - Guidelines 13. Input Output (FIO)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1148	SEI CERT Oracle Secure Coding Standard for Java - Guidelines 14. Serialization (SER)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1152	SEI CERT Oracle Secure Coding Standard for Java - Guidelines 49. Miscellaneous (MSC)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1416	Comprehensive Categorization: Resource Lifecycle Management

Vulnerability Mapping Notes

Usage	ALLOWED (this CWE ID may be used to map to real-world vulnerabilities)
Reason	Acceptable-Use
Rationale	This CWE entry is at the Base level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.
Comments	Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction.

Notes

Relationship

This entry is different from uncontrolled resource consumption (CWE-400) in that there are other weaknesses that are related to inability to control resource consumption, such as holding on to a resource too long after use, or not correctly keeping track of active resources so that they can be managed and released when they are finished (CWE-771).

Theoretical

Vulnerability theory is largely about how behaviors and resources interact. "Resource exhaustion" can be regarded as either a consequence or an attack, depending on the perspective. This entry is an attempt to reflect one of the underlying weaknesses that enable these attacks (or consequences) to take place.

Taxonomy Mappings

Mapped Taxonomy Name	Node ID	Mapped Node Name
The CERT Oracle Secure Coding Standard for Java (2011)	FIO04-J	Close resources when they are no longer needed
The CERT Oracle Secure Coding Standard for Java (2011)	SER12-J	Avoid memory and resource leaks during serialization
The CERT Oracle Secure Coding Standard for Java (2011)	MSC05-J	Do not exhaust heap space
ISA/IEC 62443	Part 4-2	Req CR 7.2
ISA/IEC 62443	Part 4-2	Req CR 2.7
ISA/IEC 62443	Part 4-1	Req SI-1
ISA/IEC 62443	Part 4-1	Req SI-2
ISA/IEC 62443	Part 3-3	Req SR 7.2
ISA/IEC 62443	Part 3-3	Req SR 2.7

Related Attack Patterns

CAPEC-ID	Attack Pattern Name
CAPEC-125	Flooding
CAPEC-130	Excessive Allocation
CAPEC-147	XML Ping of the Death
CAPEC-197	Exponential Data Expansion
CAPEC-229	Serialized Data Parameter Blowup
CAPEC-230	Serialized Data with Nested Payloads
CAPEC-231	Oversized Serialized Data Payloads
CAPEC-469	HTTP DoS
CAPEC-482	TCP Flood
CAPEC-486	UDP Flood
CAPEC-487	ICMP Flood
CAPEC-488	HTTP Flood
CAPEC-489	SSL Flood
CAPEC-490	Amplification
CAPEC-491	Quadratic Data Expansion
CAPEC-493	SOAP Array Blowup
CAPEC-494	TCP Fragmentation
CAPEC-495	UDP Fragmentation
CAPEC-496	ICMP Fragmentation
CAPEC-528	XML Flood

References

[REF-386]	Joao Antunes, Nuno Ferreira Neves and Paulo Verissimo. "Detection and Prediction of Resource-Exhaustion Vulnerabilities". Proceedings of the IEEE International Symposium on Software Reliability Engineering (ISSRE). 2008-11. <http://homepages.di.fc.ul.pt/~nuno/PAPERS/ISSRE08.pdf>.
[REF-387]	D.J. Bernstein. "Resource exhaustion". <http://cr.yp.to/docs/resources.html>.
[REF-388]	Pascal Meunier. "Resource exhaustion". Secure Programming Educational Material. 2004. <http://homes.cerias.purdue.edu/~pmeunier/secprog/sanitized/class1/6.resource%20exhaustion.ppt>.
[REF-7]	Michael Howard and David LeBlanc. "Writing Secure Code". Chapter 17, "Protecting Against Denial of Service Attacks" Page 517. 2nd Edition. Microsoft Press. 2002-12-04. <https://www.microsoftpressstore.com/store/writing-secure-code-9780735617223>.
[REF-667]	Rafal Los. "Real-Life Example of a 'Business Logic Defect' (Screen Shots!)". 2011. <http://h30501.www3.hp.com/t5/Following-the-White-Rabbit-A/Real-Life-Example-of-a-Business-Logic-Defect-Screen-Shots/ba-p/22581>.
[REF-672]	Frank Kim. "Top 25 Series - Rank 22 - Allocation of Resources Without Limits or Throttling". SANS Software Security Institute. 2010-03-23. <https://web.archive.org/web/20170113055136/https://software-security.sans.org/blog/2010/03/23/top-25-series-rank-22-allocation-of-resources-without-limits-or-throttling/>. (URL validated: 2023-04-07)
[REF-62]	Mark Dowd, John McDonald and Justin Schuh. "The Art of Software Security Assessment". Chapter 10, "Resource Limits", Page 574. 1st Edition. Addison Wesley. 2006.

Content History

Submissions
Submission Date	Submitter	Organization
2009-05-13 (CWE 1.4, 2009-05-27)	CWE Content Team	MITRE
2009-05-13 (CWE 1.4, 2009-05-27)
Contributions
Contribution Date	Contributor	Organization
2023-11-14 (CWE 4.14, 2024-02-29)	participants in the CWE ICS/OT SIG 62443 Mapping Fall Workshop
2023-11-14 (CWE 4.14, 2024-02-29)	Contributed or reviewed taxonomy mappings for ISA/IEC 62443
Modifications
Modification Date	Modifier	Organization
2024-02-29 (CWE 4.14, 2024-02-29)	CWE Content Team	MITRE
2024-02-29 (CWE 4.14, 2024-02-29)	updated Taxonomy_Mappings
2023-06-29	CWE Content Team	MITRE
2023-06-29	updated Mapping_Notes
2023-04-27	CWE Content Team	MITRE
2023-04-27	updated References, Relationships
2023-01-31	CWE Content Team	MITRE
2023-01-31	updated Description, Detection_Factors
2022-10-13	CWE Content Team	MITRE
2022-10-13	updated Observed_Examples, References
2021-07-20	CWE Content Team	MITRE
2021-07-20	updated Observed_Examples
2020-12-10	CWE Content Team	MITRE
2020-12-10	updated Relationships
2020-06-25	CWE Content Team	MITRE
2020-06-25	updated Applicable_Platforms, Description, Maintenance_Notes, Potential_Mitigations, Relationship_Notes, Relationships
2020-02-24	CWE Content Team	MITRE
2020-02-24	updated Potential_Mitigations, Related_Attack_Patterns, Relationships
2019-06-20	CWE Content Team	MITRE
2019-06-20	updated Related_Attack_Patterns, Relationships
2019-01-03	CWE Content Team	MITRE
2019-01-03	updated Demonstrative_Examples, Description, Relationships, Taxonomy_Mappings
2018-03-27	CWE Content Team	MITRE
2018-03-27	updated References
2017-11-08	CWE Content Team	MITRE
2017-11-08	updated Demonstrative_Examples, Likelihood_of_Exploit, Modes_of_Introduction, Potential_Mitigations, References, Relationships, Taxonomy_Mappings
2017-05-03	CWE Content Team	MITRE
2017-05-03	updated Related_Attack_Patterns
2015-12-07	CWE Content Team	MITRE
2015-12-07	updated Related_Attack_Patterns
2014-07-30	CWE Content Team	MITRE
2014-07-30	updated Relationships
2014-06-23	CWE Content Team	MITRE
2014-06-23	updated Related_Attack_Patterns
2014-02-18	CWE Content Team	MITRE
2014-02-18	updated Related_Attack_Patterns
2012-10-30	CWE Content Team	MITRE
2012-10-30	updated Potential_Mitigations
2012-05-11	CWE Content Team	MITRE
2012-05-11	updated Demonstrative_Examples, References, Related_Attack_Patterns, Relationships, Taxonomy_Mappings
2011-09-13	CWE Content Team	MITRE
2011-09-13	updated Relationships, Taxonomy_Mappings
2011-06-27	CWE Content Team	MITRE
2011-06-27	updated Relationships
2011-06-01	CWE Content Team	MITRE
2011-06-01	updated Common_Consequences, Relationships, Taxonomy_Mappings
2011-03-29	CWE Content Team	MITRE
2011-03-29	updated Demonstrative_Examples, Detection_Factors, Relationships
2010-09-27	CWE Content Team	MITRE
2010-09-27	updated Demonstrative_Examples, Potential_Mitigations
2010-06-21	CWE Content Team	MITRE
2010-06-21	updated Common_Consequences, Potential_Mitigations, References
2010-04-05	CWE Content Team	MITRE
2010-04-05	updated Common_Consequences, Demonstrative_Examples, Related_Attack_Patterns
2010-02-16	CWE Content Team	MITRE
2010-02-16	updated Common_Consequences, Detection_Factors, Potential_Mitigations, References, Related_Attack_Patterns, Relationships
2009-12-28	CWE Content Team	MITRE
2009-12-28	updated Applicable_Platforms, Demonstrative_Examples, Detection_Factors, Observed_Examples, References, Time_of_Introduction
2009-10-29	CWE Content Team	MITRE
2009-10-29	updated Relationships
2009-07-27	CWE Content Team	MITRE
2009-07-27	updated Related_Attack_Patterns

Weakness ID: 805

View customized information:

Description

The product uses a sequential operation to read or write a buffer, but it uses an incorrect length value that causes it to access memory that is outside of the bounds of the buffer.

Extended Description

When the length value exceeds the size of the destination, a buffer overflow could occur.

Common Consequences

Impact	Details
Read Memory; Modify Memory; Execute Unauthorized Code or Commands	Scope: Integrity, Confidentiality, Availability Buffer overflows often can be used to execute arbitrary code, which is usually outside the scope of a program's implicit security policy. This can often be used to subvert any other security service.
Modify Memory; DoS: Crash, Exit, or Restart; DoS: Resource Consumption (CPU)	Scope: Availability Buffer overflows generally lead to crashes. Other attacks leading to lack of availability are possible, including putting the program into an infinite loop.

Potential Mitigations

Phase(s)	Mitigation
Requirements	Strategy: Language Selection Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, many languages that perform their own memory management, such as Java and Perl, are not subject to buffer overflows. Other languages, such as Ada and C#, typically provide overflow protection, but the protection can be disabled by the programmer. Be wary that a language's interface to native code may still be subject to overflows, even if the language itself is theoretically safe.
Architecture and Design	Strategy: Libraries or Frameworks Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. Examples include the Safe C String Library (SafeStr) by Messier and Viega [REF-57], and the Strsafe.h library from Microsoft [REF-56]. These libraries provide safer versions of overflow-prone string-handling functions. Note: This is not a complete solution, since many buffer overflows are not related to strings.
Operation; Build and Compilation	Strategy: Environment Hardening Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index checking. D3-SFCV (Stack Frame Canary Validation) from D3FEND [REF-1334] discusses canary-based detection in detail. Effectiveness: Defense in Depth Note: This is not necessarily a complete solution, since these mechanisms only detect certain types of overflows. In addition, the result is still a denial of service, since the typical response is to exit the application.
Implementation	Consider adhering to the following rules when allocating and managing an application's memory: Double check that the buffer is as large as specified. When using functions that accept a number of bytes to copy, such as strncpy(), be aware that if the destination buffer size is equal to the source buffer size, it may not NULL-terminate the string. Check buffer boundaries if accessing the buffer in a loop and make sure there is no danger of writing past the allocated space. If necessary, truncate all input strings to a reasonable length before passing them to the copy and concatenation functions.
Architecture and Design	For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.
Operation; Build and Compilation	Strategy: Environment Hardening Run or compile the software using features or extensions that randomly arrange the positions of a program's executable and libraries in memory. Because this makes the addresses unpredictable, it can prevent an attacker from reliably jumping to exploitable code. Examples include Address Space Layout Randomization (ASLR) [REF-58] [REF-60] and Position-Independent Executables (PIE) [REF-64]. Imported modules may be similarly realigned if their default memory addresses conflict with other modules, in a process known as "rebasing" (for Windows) and "prelinking" (for Linux) [REF-1332] using randomly generated addresses. ASLR for libraries cannot be used in conjunction with prelink since it would require relocating the libraries at run-time, defeating the whole purpose of prelinking. For more information on these techniques see D3-SAOR (Segment Address Offset Randomization) from D3FEND [REF-1335]. Effectiveness: Defense in Depth Note: These techniques do not provide a complete solution. For instance, exploits frequently use a bug that discloses memory addresses in order to maximize reliability of code execution [REF-1337]. It has also been shown that a side-channel attack can bypass ASLR [REF-1333].
Operation	Strategy: Environment Hardening Use a CPU and operating system that offers Data Execution Protection (using hardware NX or XD bits) or the equivalent techniques that simulate this feature in software, such as PaX [REF-60] [REF-61]. These techniques ensure that any instruction executed is exclusively at a memory address that is part of the code segment. For more information on these techniques see D3-PSEP (Process Segment Execution Prevention) from D3FEND [REF-1336]. Effectiveness: Defense in Depth Note: This is not a complete solution, since buffer overflows could be used to overwrite nearby variables to modify the software's state in dangerous ways. In addition, it cannot be used in cases in which self-modifying code is required. Finally, an attack could still cause a denial of service, since the typical response is to exit the application.
Architecture and Design; Operation	Strategy: Environment Hardening Run your code using the lowest privileges that are required to accomplish the necessary tasks [REF-76]. If possible, create isolated accounts with limited privileges that are only used for a single task. That way, a successful attack will not immediately give the attacker access to the rest of the product or its environment. For example, database applications rarely need to run as the database administrator, especially in day-to-day operations.
Architecture and Design; Operation	Strategy: Sandbox or Jail Run the code in a "jail" or similar sandbox environment that enforces strict boundaries between the process and the operating system. This may effectively restrict which files can be accessed in a particular directory or which commands can be executed by the software. OS-level examples include the Unix chroot jail, AppArmor, and SELinux. In general, managed code may provide some protection. For example, java.io.FilePermission in the Java SecurityManager allows the software to specify restrictions on file operations. This may not be a feasible solution, and it only limits the impact to the operating system; the rest of the application may still be subject to compromise. Be careful to avoid CWE-243 and other weaknesses related to jails. Effectiveness: Limited Note: The effectiveness of this mitigation depends on the prevention capabilities of the specific sandbox or jail being used and might only help to reduce the scope of an attack, such as restricting the attacker to certain system calls or limiting the portion of the file system that can be accessed.

Relationships

Relevant to the view "Research Concepts" (View-1000)

Nature	Type	ID	Name
ChildOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	119	Improper Restriction of Operations within the Bounds of a Memory Buffer
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	806	Buffer Access Using Size of Source Buffer
CanFollow	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	130	Improper Handling of Length Parameter Inconsistency

Relevant to the view "Software Development" (View-699)

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1218	Memory Buffer Errors

Relevant to the view "CISQ Quality Measures (2020)" (View-1305)

Nature	Type	ID	Name
ChildOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	119	Improper Restriction of Operations within the Bounds of a Memory Buffer

Relevant to the view "CISQ Data Protection Measures" (View-1340)

Nature	Type	ID	Name
ChildOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	119	Improper Restriction of Operations within the Bounds of a Memory Buffer

Modes Of Introduction

Phase	Note
Implementation

Applicable Platforms

Languages

C (Often Prevalent)

C++ (Often Prevalent)

Class: Assembly (Undetermined Prevalence)

Likelihood Of Exploit

High

Demonstrative Examples

Example 1

This example takes an IP address from a user, verifies that it is well formed and then looks up the hostname and copies it into a buffer.

(bad code)

Example Language: C

void host_lookup(char *user_supplied_addr){

struct hostent *hp;
in_addr_t *addr;
char hostname[64];
in_addr_t inet_addr(const char *cp);

/*routine that ensures user_supplied_addr is in the right format for conversion */

validate_addr_form(user_supplied_addr);
addr = inet_addr(user_supplied_addr);
hp = gethostbyaddr( addr, sizeof(struct in_addr), AF_INET);
strcpy(hostname, hp->h_name);

}

This function allocates a buffer of 64 bytes to store the hostname under the assumption that the maximum length value of hostname is 64 bytes, however there is no guarantee that the hostname will not be larger than 64 bytes. If an attacker specifies an address which resolves to a very large hostname, then the function may overwrite sensitive data or even relinquish control flow to the attacker.

Note that this example also contains an unchecked return value (CWE-252) that can lead to a NULL pointer dereference (CWE-476).

Example 2

In the following example, it is possible to request that memcpy move a much larger segment of memory than assumed:

(bad code)

Example Language: C

int returnChunkSize(void *) {

/* if chunk info is valid, return the size of usable memory,

* else, return -1 to indicate an error

*/
...

}
int main() {

...
memcpy(destBuf, srcBuf, (returnChunkSize(destBuf)-1));
...

}

If returnChunkSize() happens to encounter an error it will return -1. Notice that the return value is not checked before the memcpy operation (CWE-252), so -1 can be passed as the size argument to memcpy() (CWE-805). Because memcpy() assumes that the value is unsigned, it will be interpreted as MAXINT-1 (CWE-195), and therefore will copy far more memory than is likely available to the destination buffer (CWE-787, CWE-788).

Example 3

In the following example, the source character string is copied to the dest character string using the method strncpy.

(bad code)

Example Language: C

...
char source[21] = "the character string";
char dest[12];
strncpy(dest, source, sizeof(source)-1);
...

However, in the call to strncpy the source character string is used within the sizeof call to determine the number of characters to copy. This will create a buffer overflow as the size of the source character string is greater than the dest character string. The dest character string should be used within the sizeof call to ensure that the correct number of characters are copied, as shown below.

(good code)

Example Language: C

...
char source[21] = "the character string";
char dest[12];
strncpy(dest, source, sizeof(dest)-1);
...

Example 4

In this example, the method outputFilenameToLog outputs a filename to a log file. The method arguments include a pointer to a character string containing the file name and an integer for the number of characters in the string. The filename is copied to a buffer where the buffer size is set to a maximum size for inputs to the log file. The method then calls another method to save the contents of the buffer to the log file.

(bad code)

Example Language: C

#define LOG_INPUT_SIZE 40

// saves the file name to a log file
int outputFilenameToLog(char *filename, int length) {

int success;

// buffer with size set to maximum size for input to log file
char buf[LOG_INPUT_SIZE];

// copy filename to buffer
strncpy(buf, filename, length);

// save to log file
success = saveToLogFile(buf);

return success;

}

However, in this case the string copy method, strncpy, mistakenly uses the length method argument to determine the number of characters to copy rather than using the size of the local character string, buf. This can lead to a buffer overflow if the number of characters contained in character string pointed to by filename is larger then the number of characters allowed for the local character string. The string copy method should use the buf character string within a sizeof call to ensure that only characters up to the size of the buf array are copied to avoid a buffer overflow, as shown below.

(good code)

Example Language: C

...
// copy filename to buffer
strncpy(buf, filename, sizeof(buf)-1);
...

Example 5

Windows provides the MultiByteToWideChar(), WideCharToMultiByte(), UnicodeToBytes(), and BytesToUnicode() functions to convert between arbitrary multibyte (usually ANSI) character strings and Unicode (wide character) strings. The size arguments to these functions are specified in different units, (one in bytes, the other in characters) making their use prone to error.

In a multibyte character string, each character occupies a varying number of bytes, and therefore the size of such strings is most easily specified as a total number of bytes. In Unicode, however, characters are always a fixed size, and string lengths are typically given by the number of characters they contain. Mistakenly specifying the wrong units in a size argument can lead to a buffer overflow.

The following function takes a username specified as a multibyte string and a pointer to a structure for user information and populates the structure with information about the specified user. Since Windows authentication uses Unicode for usernames, the username argument is first converted from a multibyte string to a Unicode string.

(bad code)

Example Language: C

void getUserInfo(char *username, struct _USER_INFO_2 info){

WCHAR unicodeUser[UNLEN+1];
MultiByteToWideChar(CP_ACP, 0, username, -1, unicodeUser, sizeof(unicodeUser));
NetUserGetInfo(NULL, unicodeUser, 2, (LPBYTE *)&info);

}

This function incorrectly passes the size of unicodeUser in bytes instead of characters. The call to MultiByteToWideChar() can therefore write up to (UNLEN+1)*sizeof(WCHAR) wide characters, or (UNLEN+1)*sizeof(WCHAR)*sizeof(WCHAR) bytes, to the unicodeUser array, which has only (UNLEN+1)*sizeof(WCHAR) bytes allocated.

If the username string contains more than UNLEN characters, the call to MultiByteToWideChar() will overflow the buffer unicodeUser.

Selected Observed Examples

Reference	Description
CVE-2011-1959	Chain: large length value causes buffer over-read (CWE-126)
CVE-2011-1848	Use of packet length field to make a calculation, then copy into a fixed-size buffer
CVE-2011-0105	Chain: retrieval of length value from an uninitialized memory location
CVE-2011-0606	Crafted length value in document reader leads to buffer overflow
CVE-2011-0651	SSL server overflow when the sum of multiple length fields exceeds a given value
CVE-2010-4156	Language interpreter API function doesn't validate length argument, leading to information exposure

Weakness Ordinalities

Ordinality	Description
Resultant	(where the weakness is typically related to the presence of some other weaknesses)
Primary	(where the weakness exists independent of other weaknesses)

Detection Methods

Method	Details
Automated Static Analysis	This weakness can often be detected using automated static analysis tools. Many modern tools use data flow analysis or constraint-based techniques to minimize the number of false positives. Automated static analysis generally does not account for environmental considerations when reporting out-of-bounds memory operations. This can make it difficult for users to determine which warnings should be investigated first. For example, an analysis tool might report buffer overflows that originate from command line arguments in a program that is not expected to run with setuid or other special privileges. Effectiveness: High Note:Detection techniques for buffer-related errors are more mature than for most other weakness types.
Automated Dynamic Analysis	This weakness can be detected using dynamic tools and techniques that interact with the product using large test suites with many diverse inputs, such as fuzz testing (fuzzing), robustness testing, and fault injection. The product's operation may slow down, but it should not become unstable, crash, or generate incorrect results. Effectiveness: Moderate Note:Without visibility into the code, black box methods may not be able to sufficiently distinguish this weakness from others, requiring manual methods to diagnose the underlying problem.
Manual Analysis	Manual analysis can be useful for finding this weakness, but it might not achieve desired code coverage within limited time constraints. This becomes difficult for weaknesses that must be considered for all inputs, since the attack surface can be too large.

Affected Resources

Memory

Memberships

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	740	CERT C Secure Coding Standard (2008) Chapter 7 - Arrays (ARR)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	802	2010 Top 25 - Risky Resource Management
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	867	2011 Top 25 - Weaknesses On the Cusp
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	874	CERT C++ Secure Coding Section 06 - Arrays and the STL (ARR)
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	884	CWE Cross-section
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1160	SEI CERT C Coding Standard - Guidelines 06. Arrays (ARR)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1399	Comprehensive Categorization: Memory Safety

Vulnerability Mapping Notes

Usage	ALLOWED (this CWE ID may be used to map to real-world vulnerabilities)
Reason	Acceptable-Use
Rationale	This CWE entry is at the Base level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.
Comments	Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction.

Taxonomy Mappings

Mapped Taxonomy Name	Node ID	Fit	Mapped Node Name
CERT C Secure Coding	ARR38-C	Imprecise	Guarantee that library functions do not form invalid pointers

Related Attack Patterns

CAPEC-ID	Attack Pattern Name
CAPEC-100	Overflow Buffers
CAPEC-256	SOAP Array Overflow

References

[REF-7]	Michael Howard and David LeBlanc. "Writing Secure Code". Chapter 6, "Why ACLs Are Important" Page 171. 2nd Edition. Microsoft Press. 2002-12-04. <https://www.microsoftpressstore.com/store/writing-secure-code-9780735617223>.
[REF-58]	Michael Howard. "Address Space Layout Randomization in Windows Vista". <https://learn.microsoft.com/en-us/archive/blogs/michael_howard/address-space-layout-randomization-in-windows-vista>. (URL validated: 2023-04-07)
[REF-59]	Arjan van de Ven. "Limiting buffer overflows with ExecShield". <https://archive.is/saAFo>. (URL validated: 2023-04-07)
[REF-60]	"PaX". <https://en.wikipedia.org/wiki/Executable_space_protection#PaX>. (URL validated: 2023-04-07)
[REF-741]	Jason Lam. "Top 25 Series - Rank 12 - Buffer Access with Incorrect Length Value". SANS Software Security Institute. 2010-03-11. <https://web.archive.org/web/20100316043717/http://blogs.sans.org:80/appsecstreetfighter/2010/03/11/top-25-series-rank-12-buffer-access-with-incorrect-length-value/>. (URL validated: 2023-04-07)
[REF-57]	Matt Messier and John Viega. "Safe C String Library v1.0.3". <http://www.gnu-darwin.org/www001/ports-1.5a-CURRENT/devel/safestr/work/safestr-1.0.3/doc/safestr.html>. (URL validated: 2023-04-07)
[REF-56]	Microsoft. "Using the Strsafe.h Functions". <https://learn.microsoft.com/en-us/windows/win32/menurc/strsafe-ovw?redirectedfrom=MSDN>. (URL validated: 2023-04-07)
[REF-61]	Microsoft. "Understanding DEP as a mitigation technology part 1". <https://msrc.microsoft.com/blog/2009/06/understanding-dep-as-a-mitigation-technology-part-1/>. (URL validated: 2023-04-07)
[REF-76]	Sean Barnum and Michael Gegick. "Least Privilege". 2005-09-14. <https://web.archive.org/web/20211209014121/https://www.cisa.gov/uscert/bsi/articles/knowledge/principles/least-privilege>. (URL validated: 2023-04-07)
[REF-64]	Grant Murphy. "Position Independent Executables (PIE)". Red Hat. 2012-11-28. <https://www.redhat.com/en/blog/position-independent-executables-pie>. (URL validated: 2023-04-07)
[REF-1332]	John Richard Moser. "Prelink and address space randomization". 2006-07-05. <https://lwn.net/Articles/190139/>. (URL validated: 2023-04-26)
[REF-1333]	Dmitry Evtyushkin, Dmitry Ponomarev, Nael Abu-Ghazaleh. "Jump Over ASLR: Attacking Branch Predictors to Bypass ASLR". 2016. <http://www.cs.ucr.edu/~nael/pubs/micro16.pdf>. (URL validated: 2023-04-26)
[REF-1334]	D3FEND. "Stack Frame Canary Validation (D3-SFCV)". 2023. <https://d3fend.mitre.org/technique/d3f:StackFrameCanaryValidation/>. (URL validated: 2023-04-26)
[REF-1335]	D3FEND. "Segment Address Offset Randomization (D3-SAOR)". 2023. <https://d3fend.mitre.org/technique/d3f:SegmentAddressOffsetRandomization/>. (URL validated: 2023-04-26)
[REF-1336]	D3FEND. "Process Segment Execution Prevention (D3-PSEP)". 2023. <https://d3fend.mitre.org/technique/d3f:ProcessSegmentExecutionPrevention/>. (URL validated: 2023-04-26)
[REF-1337]	Alexander Sotirov and Mark Dowd. "Bypassing Browser Memory Protections: Setting back browser security by 10 years". Memory information leaks. 2008. <https://www.blackhat.com/presentations/bh-usa-08/Sotirov_Dowd/bh08-sotirov-dowd.pdf>. (URL validated: 2023-04-26)

Content History

Submissions
Submission Date	Submitter	Organization
2010-01-15 (CWE 1.8, 2010-02-16)	CWE Content Team	MITRE
2010-01-15 (CWE 1.8, 2010-02-16)
Modifications
Modification Date	Modifier	Organization
2024-02-29 (CWE 4.14, 2024-02-29)	CWE Content Team	MITRE
2024-02-29 (CWE 4.14, 2024-02-29)	updated Demonstrative_Examples
2023-06-29	CWE Content Team	MITRE
2023-06-29	updated Mapping_Notes
2023-04-27	CWE Content Team	MITRE
2023-04-27	updated Potential_Mitigations, References, Relationships
2023-01-31	CWE Content Team	MITRE
2023-01-31	updated Description, Detection_Factors, Potential_Mitigations
2022-10-13	CWE Content Team	MITRE
2022-10-13	updated References
2021-07-20	CWE Content Team	MITRE
2021-07-20	updated Demonstrative_Examples, Potential_Mitigations
2020-12-10	CWE Content Team	MITRE
2020-12-10	updated Relationships
2020-08-20	CWE Content Team	MITRE
2020-08-20	updated Relationships
2020-06-25	CWE Content Team	MITRE
2020-06-25	updated Common_Consequences
2020-02-24	CWE Content Team	MITRE
2020-02-24	updated Relationships
2019-06-20	CWE Content Team	MITRE
2019-06-20	updated Related_Attack_Patterns
2019-01-03	CWE Content Team	MITRE
2019-01-03	updated Relationships
2018-03-27	CWE Content Team	MITRE
2018-03-27	updated References
2017-11-08	CWE Content Team	MITRE
2017-11-08	updated Applicable_Platforms, Causal_Nature, Demonstrative_Examples, Likelihood_of_Exploit, References, Taxonomy_Mappings
2014-06-23	CWE Content Team	MITRE
2014-06-23	updated Demonstrative_Examples
2014-02-18	CWE Content Team	MITRE
2014-02-18	updated Potential_Mitigations, References
2012-10-30	CWE Content Team	MITRE
2012-10-30	updated Potential_Mitigations
2012-05-11	CWE Content Team	MITRE
2012-05-11	updated Potential_Mitigations, References, Relationships
2011-09-13	CWE Content Team	MITRE
2011-09-13	updated Relationships, Taxonomy_Mappings
2011-06-27	CWE Content Team	MITRE
2011-06-27	updated Demonstrative_Examples, Observed_Examples, Relationships
2011-06-01	CWE Content Team	MITRE
2011-06-01	updated Common_Consequences
2010-12-13	CWE Content Team	MITRE
2010-12-13	updated Potential_Mitigations
2010-09-27	CWE Content Team	MITRE
2010-09-27	updated Potential_Mitigations
2010-06-21	CWE Content Team	MITRE
2010-06-21	updated Common_Consequences, Potential_Mitigations, References
2010-04-05	CWE Content Team	MITRE
2010-04-05	updated Related_Attack_Patterns

Weakness ID: 120

Vulnerability Mapping: ALLOWED This CWE ID could be used to map to real-world vulnerabilities in limited situations requiring careful review (with careful review of mapping notes)
Abstraction: Base Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.

View customized information:

Description

The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer, leading to a buffer overflow.

Extended Description

A buffer overflow condition exists when a product attempts to put more data in a buffer than it can hold, or when it attempts to put data in a memory area outside of the boundaries of a buffer. The simplest type of error, and the most common cause of buffer overflows, is the "classic" case in which the product copies the buffer without restricting how much is copied. Other variants exist, but the existence of a classic overflow strongly suggests that the programmer is not considering even the most basic of security protections.

Alternate Terms

Classic Buffer Overflow	This term was frequently used by vulnerability researchers during approximately 1995 to 2005 to differentiate buffer copies without length checks (which had been known about for decades) from other emerging weaknesses that still involved invalid accesses of buffers, as vulnerability researchers began to develop advanced exploitation techniques.
Unbounded Transfer

Common Consequences

Impact	Details
Modify Memory; Execute Unauthorized Code or Commands	Scope: Integrity, Confidentiality, Availability Buffer overflows often can be used to execute arbitrary code, which is usually outside the scope of the product's implicit security policy. This can often be used to subvert any other security service.
Modify Memory; DoS: Crash, Exit, or Restart; DoS: Resource Consumption (CPU)	Scope: Availability Buffer overflows generally lead to crashes. Other attacks leading to lack of availability are possible, including putting the product into an infinite loop.

Potential Mitigations

Phase(s)	Mitigation
Requirements	Strategy: Language Selection Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, many languages that perform their own memory management, such as Java and Perl, are not subject to buffer overflows. Other languages, such as Ada and C#, typically provide overflow protection, but the protection can be disabled by the programmer. Be wary that a language's interface to native code may still be subject to overflows, even if the language itself is theoretically safe.
Architecture and Design	Strategy: Libraries or Frameworks Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. Examples include the Safe C String Library (SafeStr) by Messier and Viega [REF-57], and the Strsafe.h library from Microsoft [REF-56]. These libraries provide safer versions of overflow-prone string-handling functions. Note: This is not a complete solution, since many buffer overflows are not related to strings.
Operation; Build and Compilation	Strategy: Environment Hardening Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index checking. D3-SFCV (Stack Frame Canary Validation) from D3FEND [REF-1334] discusses canary-based detection in detail. Effectiveness: Defense in Depth Note: This is not necessarily a complete solution, since these mechanisms only detect certain types of overflows. In addition, the result is still a denial of service, since the typical response is to exit the application.
Implementation	Consider adhering to the following rules when allocating and managing an application's memory: Double check that your buffer is as large as you specify. When using functions that accept a number of bytes to copy, such as strncpy(), be aware that if the destination buffer size is equal to the source buffer size, it may not NULL-terminate the string. Check buffer boundaries if accessing the buffer in a loop and make sure there is no danger of writing past the allocated space. If necessary, truncate all input strings to a reasonable length before passing them to the copy and concatenation functions.
Implementation	Strategy: Input Validation Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does. When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue." Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.
Architecture and Design	For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.
Operation; Build and Compilation	Strategy: Environment Hardening Run or compile the software using features or extensions that randomly arrange the positions of a program's executable and libraries in memory. Because this makes the addresses unpredictable, it can prevent an attacker from reliably jumping to exploitable code. Examples include Address Space Layout Randomization (ASLR) [REF-58] [REF-60] and Position-Independent Executables (PIE) [REF-64]. Imported modules may be similarly realigned if their default memory addresses conflict with other modules, in a process known as "rebasing" (for Windows) and "prelinking" (for Linux) [REF-1332] using randomly generated addresses. ASLR for libraries cannot be used in conjunction with prelink since it would require relocating the libraries at run-time, defeating the whole purpose of prelinking. For more information on these techniques see D3-SAOR (Segment Address Offset Randomization) from D3FEND [REF-1335]. Effectiveness: Defense in Depth Note: These techniques do not provide a complete solution. For instance, exploits frequently use a bug that discloses memory addresses in order to maximize reliability of code execution [REF-1337]. It has also been shown that a side-channel attack can bypass ASLR [REF-1333]
Operation	Strategy: Environment Hardening Use a CPU and operating system that offers Data Execution Protection (using hardware NX or XD bits) or the equivalent techniques that simulate this feature in software, such as PaX [REF-60] [REF-61]. These techniques ensure that any instruction executed is exclusively at a memory address that is part of the code segment. For more information on these techniques see D3-PSEP (Process Segment Execution Prevention) from D3FEND [REF-1336]. Effectiveness: Defense in Depth Note: This is not a complete solution, since buffer overflows could be used to overwrite nearby variables to modify the software's state in dangerous ways. In addition, it cannot be used in cases in which self-modifying code is required. Finally, an attack could still cause a denial of service, since the typical response is to exit the application.
Build and Compilation; Operation	Most mitigating technologies at the compiler or OS level to date address only a subset of buffer overflow problems and rarely provide complete protection against even that subset. It is good practice to implement strategies to increase the workload of an attacker, such as leaving the attacker to guess an unknown value that changes every program execution.
Implementation	Replace unbounded copy functions with analogous functions that support length arguments, such as strcpy with strncpy. Create these if they are not available. Effectiveness: Moderate Note: This approach is still susceptible to calculation errors, including issues such as off-by-one errors (CWE-193) and incorrectly calculating buffer lengths (CWE-131).
Architecture and Design	Strategy: Enforcement by Conversion When the set of acceptable objects, such as filenames or URLs, is limited or known, create a mapping from a set of fixed input values (such as numeric IDs) to the actual filenames or URLs, and reject all other inputs.
Architecture and Design; Operation	Strategy: Environment Hardening Run your code using the lowest privileges that are required to accomplish the necessary tasks [REF-76]. If possible, create isolated accounts with limited privileges that are only used for a single task. That way, a successful attack will not immediately give the attacker access to the rest of the software or its environment. For example, database applications rarely need to run as the database administrator, especially in day-to-day operations.
Architecture and Design; Operation	Strategy: Sandbox or Jail Run the code in a "jail" or similar sandbox environment that enforces strict boundaries between the process and the operating system. This may effectively restrict which files can be accessed in a particular directory or which commands can be executed by the software. OS-level examples include the Unix chroot jail, AppArmor, and SELinux. In general, managed code may provide some protection. For example, java.io.FilePermission in the Java SecurityManager allows the software to specify restrictions on file operations. This may not be a feasible solution, and it only limits the impact to the operating system; the rest of the application may still be subject to compromise. Be careful to avoid CWE-243 and other weaknesses related to jails. Effectiveness: Limited Note: The effectiveness of this mitigation depends on the prevention capabilities of the specific sandbox or jail being used and might only help to reduce the scope of an attack, such as restricting the attacker to certain system calls or limiting the portion of the file system that can be accessed.

Relationships

Relevant to the view "Research Concepts" (View-1000)

Nature	Type	ID	Name
ChildOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	787	Out-of-bounds Write
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	785	Use of Path Manipulation Function without Maximum-sized Buffer
CanFollow	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	170	Improper Null Termination
CanFollow	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	231	Improper Handling of Extra Values
CanFollow	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	416	Use After Free
CanFollow	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	456	Missing Initialization of a Variable
CanPrecede	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	123	Write-what-where Condition

Relevant to the view "Software Development" (View-699)

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1218	Memory Buffer Errors

Relevant to the view "Weaknesses for Simplified Mapping of Published Vulnerabilities" (View-1003)

Nature	Type	ID	Name
ChildOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	119	Improper Restriction of Operations within the Bounds of a Memory Buffer

Relevant to the view "CISQ Quality Measures (2020)" (View-1305)

Nature	Type	ID	Name
ChildOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	787	Out-of-bounds Write

Relevant to the view "CISQ Data Protection Measures" (View-1340)

Nature	Type	ID	Name
ChildOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	787	Out-of-bounds Write

Relevant to the view "Seven Pernicious Kingdoms" (View-700)

Nature	Type	ID	Name
ChildOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	20	Improper Input Validation

Modes Of Introduction

Phase	Note
Implementation

Applicable Platforms

Languages

C (Often Prevalent)

C++ (Often Prevalent)

Class: Assembly (Undetermined Prevalence)

Likelihood Of Exploit

High

Demonstrative Examples

Example 1

The following code asks the user to enter their last name and then attempts to store the value entered in the last_name array.

(bad code)

Example Language: C

char last_name[20];
printf ("Enter your last name: ");
scanf ("%s", last_name);

The problem with the code above is that it does not restrict or limit the size of the name entered by the user. If the user enters "Very_very_long_last_name" which is 24 characters long, then a buffer overflow will occur since the array can only hold 20 characters total.

Example 2

The following code attempts to create a local copy of a buffer to perform some manipulations to the data.

(bad code)

Example Language: C

void manipulate_string(char * string){

char buf[24];
strcpy(buf, string);
...

}

However, the programmer does not ensure that the size of the data pointed to by string will fit in the local buffer and copies the data with the potentially dangerous strcpy() function. This may result in a buffer overflow condition if an attacker can influence the contents of the string parameter.

Example 3

The code below calls the gets() function to read in data from the command line.

(bad code)

Example Language: C

char buf[24];
printf("Please enter your name and press <Enter>\n");
gets(buf);
...

}

However, gets() is inherently unsafe, because it copies all input from STDIN to the buffer without checking size. This allows the user to provide a string that is larger than the buffer size, resulting in an overflow condition.

Example 4

In the following example, a server accepts connections from a client and processes the client request. After accepting a client connection, the program will obtain client information using the gethostbyaddr method, copy the hostname of the client that connected to a local variable and output the hostname of the client to a log file.

(bad code)

Example Language: C

...

struct hostent *clienthp;
char hostname[MAX_LEN];

// create server socket, bind to server address and listen on socket
...

// accept client connections and process requests
int count = 0;
for (count = 0; count < MAX_CONNECTIONS; count++) {

int clientlen = sizeof(struct sockaddr_in);
int clientsocket = accept(serversocket, (struct sockaddr *)&clientaddr, &clientlen);

if (clientsocket >= 0) {

clienthp = gethostbyaddr((char*) &clientaddr.sin_addr.s_addr, sizeof(clientaddr.sin_addr.s_addr), AF_INET);
strcpy(hostname, clienthp->h_name);
logOutput("Accepted client connection from host ", hostname);

// process client request
...
close(clientsocket);

}

}
close(serversocket);

...

However, the hostname of the client that connected may be longer than the allocated size for the local hostname variable. This will result in a buffer overflow when copying the client hostname to the local variable using the strcpy method.

Selected Observed Examples

Reference	Description
CVE-2000-1094	buffer overflow using command with long argument
CVE-1999-0046	buffer overflow in local program using long environment variable
CVE-2002-1337	buffer overflow in comment characters, when product increments a counter for a ">" but does not decrement for "<"
CVE-2003-0595	By replacing a valid cookie value with an extremely long string of characters, an attacker may overflow the application's buffers.
CVE-2001-0191	By replacing a valid cookie value with an extremely long string of characters, an attacker may overflow the application's buffers.

Weakness Ordinalities

Ordinality	Description
Resultant	(where the weakness is typically related to the presence of some other weaknesses)
Primary	(where the weakness exists independent of other weaknesses)

Detection Methods

Method	Details
Automated Static Analysis	This weakness can often be detected using automated static analysis tools. Many modern tools use data flow analysis or constraint-based techniques to minimize the number of false positives. Automated static analysis generally does not account for environmental considerations when reporting out-of-bounds memory operations. This can make it difficult for users to determine which warnings should be investigated first. For example, an analysis tool might report buffer overflows that originate from command line arguments in a program that is not expected to run with setuid or other special privileges. Effectiveness: High Note:Detection techniques for buffer-related errors are more mature than for most other weakness types.
Automated Dynamic Analysis	This weakness can be detected using dynamic tools and techniques that interact with the software using large test suites with many diverse inputs, such as fuzz testing (fuzzing), robustness testing, and fault injection. The software's operation may slow down, but it should not become unstable, crash, or generate incorrect results.
Manual Analysis	Manual analysis can be useful for finding this weakness, but it might not achieve desired code coverage within limited time constraints. This becomes difficult for weaknesses that must be considered for all inputs, since the attack surface can be too large.
Automated Static Analysis - Binary or Bytecode	According to SOAR, the following detection techniques may be useful: Highly cost effective: Bytecode Weakness Analysis - including disassembler + source code weakness analysis Binary Weakness Analysis - including disassembler + source code weakness analysis Effectiveness: High
Manual Static Analysis - Binary or Bytecode	According to SOAR, the following detection techniques may be useful: Cost effective for partial coverage: Binary / Bytecode disassembler - then use manual analysis for vulnerabilities & anomalies Effectiveness: SOAR Partial
Dynamic Analysis with Automated Results Interpretation	According to SOAR, the following detection techniques may be useful: Cost effective for partial coverage: Web Application Scanner Web Services Scanner Database Scanners Effectiveness: SOAR Partial
Dynamic Analysis with Manual Results Interpretation	According to SOAR, the following detection techniques may be useful: Cost effective for partial coverage: Fuzz Tester Framework-based Fuzzer Effectiveness: SOAR Partial
Manual Static Analysis - Source Code	According to SOAR, the following detection techniques may be useful: Cost effective for partial coverage: Focused Manual Spotcheck - Focused manual analysis of source Manual Source Code Review (not inspections) Effectiveness: SOAR Partial
Automated Static Analysis - Source Code	According to SOAR, the following detection techniques may be useful: Highly cost effective: Source code Weakness Analyzer Context-configured Source Code Weakness Analyzer Effectiveness: High
Architecture or Design Review	According to SOAR, the following detection techniques may be useful: Highly cost effective: Formal Methods / Correct-By-Construction Cost effective for partial coverage: Inspection (IEEE 1028 standard) (can apply to requirements, design, source code, etc.) Effectiveness: High

Functional Areas

Memory Management

Affected Resources

Memory

Memberships

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	722	OWASP Top Ten 2004 Category A1 - Unvalidated Input
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	726	OWASP Top Ten 2004 Category A5 - Buffer Overflows
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	741	CERT C Secure Coding Standard (2008) Chapter 8 - Characters and Strings (STR)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	802	2010 Top 25 - Risky Resource Management
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	865	2011 Top 25 - Risky Resource Management
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	875	CERT C++ Secure Coding Section 07 - Characters and Strings (STR)
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	884	CWE Cross-section
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	970	SFP Secondary Cluster: Faulty Buffer Access
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1129	CISQ Quality Measures (2016) - Reliability
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1131	CISQ Quality Measures (2016) - Security
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1161	SEI CERT C Coding Standard - Guidelines 07. Characters and Strings (STR)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1399	Comprehensive Categorization: Memory Safety

Vulnerability Mapping Notes

Usage	ALLOWED-WITH-REVIEW (this CWE ID could be used to map to real-world vulnerabilities in limited situations requiring careful review)
Reason	Frequent Misuse
Rationale	There are some indications that this CWE ID might be misused and selected simply because it mentions "buffer overflow" - an increasingly vague term. This CWE entry is only appropriate for "Buffer Copy" operations (not buffer reads), in which where there is no "Checking [the] Size of Input", and (by implication of the copy) writing past the end of the buffer.
Comments	If the vulnerability being analyzed involves out-of-bounds reads, then consider CWE-125 or descendants. For root cause analysis: if there is any input validation, consider children of CWE-20 such as CWE-1284. If there is a calculation error for buffer sizes, consider CWE-131 or similar.

Notes

Relationship

At the code level, stack-based and heap-based overflows do not differ significantly, so there usually is not a need to distinguish them. From the attacker perspective, they can be quite different, since different techniques are required to exploit them.

Terminology

Many issues that are now called "buffer overflows" are substantively different than the "classic" overflow, including entirely different bug types that rely on overflow exploit techniques, such as integer signedness errors, integer overflows, and format string bugs. This imprecise terminology can make it difficult to determine which variant is being reported.

Taxonomy Mappings

Mapped Taxonomy Name	Node ID	Fit	Mapped Node Name
PLOVER			Unbounded Transfer ('classic overflow')
7 Pernicious Kingdoms			Buffer Overflow
CLASP			Buffer overflow
OWASP Top Ten 2004	A1	CWE More Specific	Unvalidated Input
OWASP Top Ten 2004	A5	CWE More Specific	Buffer Overflows
CERT C Secure Coding	STR31-C	Exact	Guarantee that storage for strings has sufficient space for character data and the null terminator
WASC	7		Buffer Overflow
Software Fault Patterns	SFP8		Faulty Buffer Access
OMG ASCSM	ASCSM-CWE-120
OMG ASCRM	ASCRM-CWE-120

Related Attack Patterns

CAPEC-ID	Attack Pattern Name
CAPEC-10	Buffer Overflow via Environment Variables
CAPEC-100	Overflow Buffers
CAPEC-14	Client-side Injection-induced Buffer Overflow
CAPEC-24	Filter Failure through Buffer Overflow
CAPEC-42	MIME Conversion
CAPEC-44	Overflow Binary Resource File
CAPEC-45	Buffer Overflow via Symbolic Links
CAPEC-46	Overflow Variables and Tags
CAPEC-47	Buffer Overflow via Parameter Expansion
CAPEC-67	String Format Overflow in syslog()
CAPEC-8	Buffer Overflow in an API Call
CAPEC-9	Buffer Overflow in Local Command-Line Utilities
CAPEC-92	Forced Integer Overflow

References

[REF-7]	Michael Howard and David LeBlanc. "Writing Secure Code". Chapter 5, "Public Enemy #1: The Buffer Overrun" Page 127. 2nd Edition. Microsoft Press. 2002-12-04. <https://www.microsoftpressstore.com/store/writing-secure-code-9780735617223>.
[REF-44]	Michael Howard, David LeBlanc and John Viega. "24 Deadly Sins of Software Security". "Sin 5: Buffer Overruns." Page 89. McGraw-Hill. 2010.
[REF-56]	Microsoft. "Using the Strsafe.h Functions". <https://learn.microsoft.com/en-us/windows/win32/menurc/strsafe-ovw?redirectedfrom=MSDN>. (URL validated: 2023-04-07)
[REF-57]	Matt Messier and John Viega. "Safe C String Library v1.0.3". <http://www.gnu-darwin.org/www001/ports-1.5a-CURRENT/devel/safestr/work/safestr-1.0.3/doc/safestr.html>. (URL validated: 2023-04-07)
[REF-58]	Michael Howard. "Address Space Layout Randomization in Windows Vista". <https://learn.microsoft.com/en-us/archive/blogs/michael_howard/address-space-layout-randomization-in-windows-vista>. (URL validated: 2023-04-07)
[REF-59]	Arjan van de Ven. "Limiting buffer overflows with ExecShield". <https://archive.is/saAFo>. (URL validated: 2023-04-07)
[REF-60]	"PaX". <https://en.wikipedia.org/wiki/Executable_space_protection#PaX>. (URL validated: 2023-04-07)
[REF-74]	Jason Lam. "Top 25 Series - Rank 3 - Classic Buffer Overflow". SANS Software Security Institute. 2010-03-02. <http://software-security.sans.org/blog/2010/03/02/top-25-series-rank-3-classic-buffer-overflow/>.
[REF-61]	Microsoft. "Understanding DEP as a mitigation technology part 1". <https://msrc.microsoft.com/blog/2009/06/understanding-dep-as-a-mitigation-technology-part-1/>. (URL validated: 2023-04-07)
[REF-76]	Sean Barnum and Michael Gegick. "Least Privilege". 2005-09-14. <https://web.archive.org/web/20211209014121/https://www.cisa.gov/uscert/bsi/articles/knowledge/principles/least-privilege>. (URL validated: 2023-04-07)
[REF-62]	Mark Dowd, John McDonald and Justin Schuh. "The Art of Software Security Assessment". Chapter 3, "Nonexecutable Stack", Page 76. 1st Edition. Addison Wesley. 2006.
[REF-62]	Mark Dowd, John McDonald and Justin Schuh. "The Art of Software Security Assessment". Chapter 5, "Protection Mechanisms", Page 189. 1st Edition. Addison Wesley. 2006.
[REF-62]	Mark Dowd, John McDonald and Justin Schuh. "The Art of Software Security Assessment". Chapter 8, "C String Handling", Page 388. 1st Edition. Addison Wesley. 2006.
[REF-64]	Grant Murphy. "Position Independent Executables (PIE)". Red Hat. 2012-11-28. <https://www.redhat.com/en/blog/position-independent-executables-pie>. (URL validated: 2023-04-07)
[REF-961]	Object Management Group (OMG). "Automated Source Code Reliability Measure (ASCRM)". ASCRM-CWE-120. 2016-01. <http://www.omg.org/spec/ASCRM/1.0/>.
[REF-962]	Object Management Group (OMG). "Automated Source Code Security Measure (ASCSM)". ASCSM-CWE-120. 2016-01. <http://www.omg.org/spec/ASCSM/1.0/>.
[REF-1332]	John Richard Moser. "Prelink and address space randomization". 2006-07-05. <https://lwn.net/Articles/190139/>. (URL validated: 2023-04-26)
[REF-1333]	Dmitry Evtyushkin, Dmitry Ponomarev, Nael Abu-Ghazaleh. "Jump Over ASLR: Attacking Branch Predictors to Bypass ASLR". 2016. <http://www.cs.ucr.edu/~nael/pubs/micro16.pdf>. (URL validated: 2023-04-26)
[REF-1334]	D3FEND. "Stack Frame Canary Validation (D3-SFCV)". 2023. <https://d3fend.mitre.org/technique/d3f:StackFrameCanaryValidation/>. (URL validated: 2023-04-26)
[REF-1335]	D3FEND. "Segment Address Offset Randomization (D3-SAOR)". 2023. <https://d3fend.mitre.org/technique/d3f:SegmentAddressOffsetRandomization/>. (URL validated: 2023-04-26)
[REF-1336]	D3FEND. "Process Segment Execution Prevention (D3-PSEP)". 2023. <https://d3fend.mitre.org/technique/d3f:ProcessSegmentExecutionPrevention/>. (URL validated: 2023-04-26)
[REF-1337]	Alexander Sotirov and Mark Dowd. "Bypassing Browser Memory Protections: Setting back browser security by 10 years". Memory information leaks. 2008. <https://www.blackhat.com/presentations/bh-usa-08/Sotirov_Dowd/bh08-sotirov-dowd.pdf>. (URL validated: 2023-04-26)

Content History

Submissions
Submission Date	Submitter	Organization
2006-07-19 (CWE Draft 3, 2006-07-19)	PLOVER
2006-07-19 (CWE Draft 3, 2006-07-19)
Modifications
Modification Date	Modifier	Organization
2025-04-03 (CWE 4.17, 2025-04-03)	CWE Content Team	MITRE
2025-04-03 (CWE 4.17, 2025-04-03)	updated Applicable_Platforms, Relationships
2023-06-29	CWE Content Team	MITRE
2023-06-29	updated Mapping_Notes
2023-04-27	CWE Content Team	MITRE
2023-04-27	updated Potential_Mitigations, References, Relationships
2023-01-31	CWE Content Team	MITRE
2023-01-31	updated Common_Consequences, Description
2022-10-13	CWE Content Team	MITRE
2022-10-13	updated References
2021-07-20	CWE Content Team	MITRE
2021-07-20	updated Potential_Mitigations
2021-03-15	CWE Content Team	MITRE
2021-03-15	updated Demonstrative_Examples
2020-12-10	CWE Content Team	MITRE
2020-12-10	updated Demonstrative_Examples, Relationships
2020-08-20	CWE Content Team	MITRE
2020-08-20	updated Alternate_Terms, Relationships
2020-06-25	CWE Content Team	MITRE
2020-06-25	updated Common_Consequences, Potential_Mitigations
2020-02-24	CWE Content Team	MITRE
2020-02-24	updated Potential_Mitigations, Relationships
2019-06-20	CWE Content Team	MITRE
2019-06-20	updated Relationships
2019-01-03	CWE Content Team	MITRE
2019-01-03	updated References, Relationships, Taxonomy_Mappings
2018-03-27	CWE Content Team	MITRE
2018-03-27	updated References
2017-11-08	CWE Content Team	MITRE
2017-11-08	updated Applicable_Platforms, Causal_Nature, Demonstrative_Examples, Likelihood_of_Exploit, References, Relationships, Taxonomy_Mappings, White_Box_Definitions
2014-07-30	CWE Content Team	MITRE
2014-07-30	updated Detection_Factors, Relationships, Taxonomy_Mappings
2014-02-18	CWE Content Team	MITRE
2014-02-18	updated Potential_Mitigations, References
2012-10-30	CWE Content Team	MITRE
2012-10-30	updated Potential_Mitigations
2012-05-11	CWE Content Team	MITRE
2012-05-11	updated References, Relationships
2011-09-13	CWE Content Team	MITRE
2011-09-13	updated Potential_Mitigations, References, Relationships, Taxonomy_Mappings
2011-06-27	CWE Content Team	MITRE
2011-06-27	updated Relationships
2011-06-01	CWE Content Team	MITRE
2011-06-01	updated Common_Consequences
2011-03-29	CWE Content Team	MITRE
2011-03-29	updated Demonstrative_Examples, Description
2010-12-13	CWE Content Team	MITRE
2010-12-13	updated Potential_Mitigations
2010-09-27	CWE Content Team	MITRE
2010-09-27	updated Potential_Mitigations
2010-06-21	CWE Content Team	MITRE
2010-06-21	updated Common_Consequences, Potential_Mitigations, References
2010-04-05	CWE Content Team	MITRE
2010-04-05	updated Demonstrative_Examples, Related_Attack_Patterns
2010-02-16	CWE Content Team	MITRE
2010-02-16	updated Applicable_Platforms, Common_Consequences, Demonstrative_Examples, Detection_Factors, Potential_Mitigations, References, Related_Attack_Patterns, Relationships, Taxonomy_Mappings, Time_of_Introduction, Type
2009-10-29	CWE Content Team	MITRE
2009-10-29	updated Common_Consequences, Relationships
2009-07-27	CWE Content Team	MITRE
2009-07-27	updated Other_Notes, Potential_Mitigations, Relationships
2009-01-12	CWE Content Team	MITRE
2009-01-12	updated Common_Consequences, Other_Notes, Potential_Mitigations, References, Relationship_Notes, Relationships
2008-11-24	CWE Content Team	MITRE
2008-11-24	updated Other_Notes, Relationships, Taxonomy_Mappings
2008-10-14	CWE Content Team	MITRE
2008-10-14	updated Alternate_Terms, Description, Name, Other_Notes, Terminology_Notes
2008-10-10	CWE Content Team	MITRE
2008-10-10	Changed name and description to more clearly emphasize the "classic" nature of the overflow.
2008-09-08	CWE Content Team	MITRE
2008-09-08	updated Alternate_Terms, Applicable_Platforms, Common_Consequences, Relationships, Observed_Example, Other_Notes, Taxonomy_Mappings, Weakness_Ordinalities
2008-08-15		Veracode
2008-08-15	Suggested OWASP Top Ten 2004 mapping
2008-08-01		KDM Analytics
2008-08-01	added/updated white box definitions
2008-07-01	Eric Dalci	Cigital
2008-07-01	updated Time_of_Introduction
Previous Entry Names
Change Date	Previous Entry Name
2008-10-14	Unbounded Transfer ('Classic Buffer Overflow')

Weakness ID: 362

Vulnerability Mapping: ALLOWED This CWE ID could be used to map to real-world vulnerabilities in limited situations requiring careful review (with careful review of mapping notes)
Abstraction: Class Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.

View customized information:

Description

Extended Description

A race condition occurs within concurrent environments, and it is effectively a property of a code sequence. Depending on the context, a code sequence may be in the form of a function call, a small number of instructions, a series of program invocations, etc.

A race condition violates these properties, which are closely related:

Exclusivity - the code sequence is given exclusive access to the shared resource, i.e., no other code sequence can modify properties of the shared resource before the original sequence has completed execution.
Atomicity - the code sequence is behaviorally atomic, i.e., no other thread or process can concurrently execute the same sequence of instructions (or a subset) against the same resource.

A race condition exists when an "interfering code sequence" can still access the shared resource, violating exclusivity.

The interfering code sequence could be "trusted" or "untrusted." A trusted interfering code sequence occurs within the product; it cannot be modified by the attacker, and it can only be invoked indirectly. An untrusted interfering code sequence can be authored directly by the attacker, and typically it is external to the vulnerable product.

Alternate Terms

Race Condition

Common Consequences

Impact	Details
DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory); DoS: Resource Consumption (Other)	Scope: Availability When a race condition makes it possible to bypass a resource cleanup routine or trigger multiple initialization routines, it may lead to resource exhaustion.
DoS: Crash, Exit, or Restart; DoS: Instability	Scope: Availability When a race condition allows multiple control flows to access a resource simultaneously, it might lead the product(s) into unexpected states, possibly resulting in a crash.
Read Files or Directories; Read Application Data	Scope: Confidentiality, Integrity When a race condition is combined with predictable resource names and loose permissions, it may be possible for an attacker to overwrite or access confidential data (CWE-59).
Execute Unauthorized Code or Commands; Gain Privileges or Assume Identity; Bypass Protection Mechanism	Scope: Access Control This can have security implications when the expected synchronization is in security-critical code, such as recording whether a user is authenticated or modifying important state information that should not be influenced by an outsider.

Potential Mitigations

Phase(s)	Mitigation
Architecture and Design	In languages that support it, use synchronization primitives. Only wrap these around critical code to minimize the impact on performance.
Architecture and Design	Use thread-safe capabilities such as the data access abstraction in Spring.
Architecture and Design	Minimize the usage of shared resources in order to remove as much complexity as possible from the control flow and to reduce the likelihood of unexpected conditions occurring. Additionally, this will minimize the amount of synchronization necessary and may even help to reduce the likelihood of a denial of service where an attacker may be able to repeatedly trigger a critical section (CWE-400).
Implementation	When using multithreading and operating on shared variables, only use thread-safe functions.
Implementation	Use atomic operations on shared variables. Be wary of innocent-looking constructs such as "x++". This may appear atomic at the code layer, but it is actually non-atomic at the instruction layer, since it involves a read, followed by a computation, followed by a write.
Implementation	Use a mutex if available, but be sure to avoid related weaknesses such as CWE-412.
Implementation	Avoid double-checked locking (CWE-609) and other implementation errors that arise when trying to avoid the overhead of synchronization.
Implementation	Disable interrupts or signals over critical parts of the code, but also make sure that the code does not go into a large or infinite loop.
Implementation	Use the volatile type modifier for critical variables to avoid unexpected compiler optimization or reordering. This does not necessarily solve the synchronization problem, but it can help.
Architecture and Design; Operation	Strategy: Environment Hardening Run your code using the lowest privileges that are required to accomplish the necessary tasks [REF-76]. If possible, create isolated accounts with limited privileges that are only used for a single task. That way, a successful attack will not immediately give the attacker access to the rest of the software or its environment. For example, database applications rarely need to run as the database administrator, especially in day-to-day operations.

Relationships

Relevant to the view "Research Concepts" (View-1000)

Nature	Type	ID	Name
ChildOf	Pillar - a weakness that is the most abstract type of weakness and represents a theme for all class/base/variant weaknesses related to it. A Pillar is different from a Category as a Pillar is still technically a type of weakness that describes a mistake, while a Category represents a common characteristic used to group related things.	691	Insufficient Control Flow Management
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	364	Signal Handler Race Condition
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	366	Race Condition within a Thread
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	367	Time-of-check Time-of-use (TOCTOU) Race Condition
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	368	Context Switching Race Condition
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	421	Race Condition During Access to Alternate Channel
ParentOf	Composite - a Compound Element that consists of two or more distinct weaknesses, in which all weaknesses must be present at the same time in order for a potential vulnerability to arise. Removing any of the weaknesses eliminates or sharply reduces the risk. One weakness, X, can be "broken down" into component weaknesses Y and Z. There can be cases in which one weakness might not be essential to a composite, but changes the nature of the composite when it becomes a vulnerability.	689	Permission Race Condition During Resource Copy
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	1223	Race Condition for Write-Once Attributes
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	1298	Hardware Logic Contains Race Conditions
CanFollow	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	662	Improper Synchronization
CanPrecede	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	416	Use After Free
CanPrecede	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	476	NULL Pointer Dereference

Relevant to the view "Weaknesses for Simplified Mapping of Published Vulnerabilities" (View-1003)

Nature	Type	ID	Name
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1003	Weaknesses for Simplified Mapping of Published Vulnerabilities
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	367	Time-of-check Time-of-use (TOCTOU) Race Condition

Modes Of Introduction

Phase

Note

Architecture and Design

Implementation

Programmers may assume that certain code sequences execute too quickly to be affected by an interfering code sequence; when they are not, this violates atomicity. For example, the single "x++" statement may appear atomic at the code layer, but it is actually non-atomic at the instruction layer, since it involves a read (the original value of x), followed by a computation (x+1), followed by a write (save the result to x).

Applicable Platforms

Languages	C (Sometimes Prevalent) C++ (Sometimes Prevalent) Java (Sometimes Prevalent)
Technologies	Class: Mobile (Undetermined Prevalence) Class: ICS/OT (Undetermined Prevalence)

Likelihood Of Exploit

Medium

Demonstrative Examples

Example 1

This code could be used in an e-commerce application that supports transfers between accounts. It takes the total amount of the transfer, sends it to the new account, and deducts the amount from the original account.

(bad code)

Example Language: Perl

$transfer_amount = GetTransferAmount();
$balance = GetBalanceFromDatabase();

if ($transfer_amount < 0) {

FatalError("Bad Transfer Amount");

}
$newbalance = $balance - $transfer_amount;
if (($balance - $transfer_amount) < 0) {

FatalError("Insufficient Funds");

}
SendNewBalanceToDatabase($newbalance);
NotifyUser("Transfer of $transfer_amount succeeded.");
NotifyUser("New balance: $newbalance");

A race condition could occur between the calls to GetBalanceFromDatabase() and SendNewBalanceToDatabase().

Suppose the balance is initially 100.00. An attack could be constructed as follows:

(attack code)

Example Language: Other

In the following pseudocode, the attacker makes two simultaneous calls of the program, CALLER-1 and CALLER-2. Both callers are for the same user account.
CALLER-1 (the attacker) is associated with PROGRAM-1 (the instance that handles CALLER-1). CALLER-2 is associated with PROGRAM-2.
CALLER-1 makes a transfer request of 80.00.
PROGRAM-1 calls GetBalanceFromDatabase and sets $balance to 100.00
PROGRAM-1 calculates $newbalance as 20.00, then calls SendNewBalanceToDatabase().
Due to high server load, the PROGRAM-1 call to SendNewBalanceToDatabase() encounters a delay.
CALLER-2 makes a transfer request of 1.00.
PROGRAM-2 calls GetBalanceFromDatabase() and sets $balance to 100.00. This happens because the previous PROGRAM-1 request was not processed yet.
PROGRAM-2 determines the new balance as 99.00.
After the initial delay, PROGRAM-1 commits its balance to the database, setting it to 20.00.
PROGRAM-2 sends a request to update the database, setting the balance to 99.00

At this stage, the attacker should have a balance of 19.00 (due to 81.00 worth of transfers), but the balance is 99.00, as recorded in the database.

To prevent this weakness, the programmer has several options, including using a lock to prevent multiple simultaneous requests to the web application, or using a synchronization mechanism that includes all the code between GetBalanceFromDatabase() and SendNewBalanceToDatabase().

Example 2

The following function attempts to acquire a lock in order to perform operations on a shared resource.

(bad code)

Example Language: C

void f(pthread_mutex_t *mutex) {

pthread_mutex_lock(mutex);

/* access shared resource */

pthread_mutex_unlock(mutex);

}

However, the code does not check the value returned by pthread_mutex_lock() for errors. If pthread_mutex_lock() cannot acquire the mutex for any reason, the function may introduce a race condition into the program and result in undefined behavior.

In order to avoid data races, correctly written programs must check the result of thread synchronization functions and appropriately handle all errors, either by attempting to recover from them or reporting them to higher levels.

(good code)

Example Language: C

int f(pthread_mutex_t *mutex) {

int result;

result = pthread_mutex_lock(mutex);
if (0 != result)

return result;

/* access shared resource */

return pthread_mutex_unlock(mutex);

}

Example 3

Suppose a processor's Memory Management Unit (MMU) has 5 other shadow MMUs to distribute its workload for its various cores. Each MMU has the start address and end address of "accessible" memory. Any time this accessible range changes (as per the processor's boot status), the main MMU sends an update message to all the shadow MMUs.

Suppose the interconnect fabric does not prioritize such "update" packets over other general traffic packets. This introduces a race condition. If an attacker can flood the target with enough messages so that some of those attack packets reach the target before the new access ranges gets updated, then the attacker can leverage this scenario.

Selected Observed Examples

Reference	Description
CVE-2022-29527	Go application for cloud management creates a world-writable sudoers file that allows local attackers to inject sudo rules and escalate privileges to root by winning a race condition.
CVE-2021-1782	Chain: improper locking (CWE-667) leads to race condition (CWE-362), as exploited in the wild per CISA KEV.
CVE-2021-0920	Chain: mobile platform race condition (CWE-362) leading to use-after-free (CWE-416), as exploited in the wild per CISA KEV.
CVE-2020-6819	Chain: race condition (CWE-362) leads to use-after-free (CWE-416), as exploited in the wild per CISA KEV.
CVE-2019-18827	chain: JTAG interface is not disabled (CWE-1191) during ROM code execution, introducing a race condition (CWE-362) to extract encryption keys
CVE-2019-1161	Chain: race condition (CWE-362) in anti-malware product allows deletion of files by creating a junction (CWE-1386) and using hard links during the time window in which a temporary file is created and deleted.
CVE-2015-1743	TOCTOU in sandbox process allows installation of untrusted browser add-ons by replacing a file after it has been verified, but before it is executed
CVE-2014-8273	Chain: chipset has a race condition (CWE-362) between when an interrupt handler detects an attempt to write-enable the BIOS (in violation of the lock bit), and when the handler resets the write-enable bit back to 0, allowing attackers to issue BIOS writes during the timing window [REF-1237].
CVE-2008-5044	Race condition leading to a crash by calling a hook removal procedure while other activities are occurring at the same time.
CVE-2008-2958	chain: time-of-check time-of-use (TOCTOU) race condition in program allows bypass of protection mechanism that was designed to prevent symlink attacks.
CVE-2008-1570	chain: time-of-check time-of-use (TOCTOU) race condition in program allows bypass of protection mechanism that was designed to prevent symlink attacks.
CVE-2008-0058	Unsynchronized caching operation enables a race condition that causes messages to be sent to a deallocated object.
CVE-2008-0379	Race condition during initialization triggers a buffer overflow.
CVE-2007-6599	Daemon crash by quickly performing operations and undoing them, which eventually leads to an operation that does not acquire a lock.
CVE-2007-6180	chain: race condition triggers NULL pointer dereference
CVE-2007-5794	Race condition in library function could cause data to be sent to the wrong process.
CVE-2007-3970	Race condition in file parser leads to heap corruption.
CVE-2008-5021	chain: race condition allows attacker to access an object while it is still being initialized, causing software to access uninitialized memory.
CVE-2009-4895	chain: race condition for an argument value, possibly resulting in NULL dereference
CVE-2009-3547	chain: race condition might allow resource to be released before operating on it, leading to NULL dereference
CVE-2006-5051	Chain: Signal handler contains too much functionality (CWE-828), introducing a race condition (CWE-362) that leads to a double free (CWE-415).

Detection Methods

Method	Details
Black Box	Black box methods may be able to identify evidence of race conditions via methods such as multiple simultaneous connections, which may cause the software to become instable or crash. However, race conditions with very narrow timing windows would not be detectable.
White Box	Common idioms are detectable in white box analysis, such as time-of-check-time-of-use (TOCTOU) file operations (CWE-367), or double-checked locking (CWE-609).
Automated Dynamic Analysis	This weakness can be detected using dynamic tools and techniques that interact with the software using large test suites with many diverse inputs, such as fuzz testing (fuzzing), robustness testing, and fault injection. The software's operation may slow down, but it should not become unstable, crash, or generate incorrect results. Race conditions may be detected with a stress-test by calling the software simultaneously from a large number of threads or processes, and look for evidence of any unexpected behavior. Insert breakpoints or delays in between relevant code statements to artificially expand the race window so that it will be easier to detect. Effectiveness: Moderate
Automated Static Analysis - Binary or Bytecode	According to SOAR, the following detection techniques may be useful: Highly cost effective: Bytecode Weakness Analysis - including disassembler + source code weakness analysis Cost effective for partial coverage: Binary Weakness Analysis - including disassembler + source code weakness analysis Effectiveness: High
Dynamic Analysis with Automated Results Interpretation	According to SOAR, the following detection techniques may be useful: Cost effective for partial coverage: Web Application Scanner Web Services Scanner Database Scanners Effectiveness: SOAR Partial
Dynamic Analysis with Manual Results Interpretation	According to SOAR, the following detection techniques may be useful: Highly cost effective: Framework-based Fuzzer Cost effective for partial coverage: Fuzz Tester Monitored Virtual Environment - run potentially malicious code in sandbox / wrapper / virtual machine, see if it does anything suspicious Effectiveness: High
Manual Static Analysis - Source Code	According to SOAR, the following detection techniques may be useful: Highly cost effective: Manual Source Code Review (not inspections) Cost effective for partial coverage: Focused Manual Spotcheck - Focused manual analysis of source Effectiveness: High
Automated Static Analysis - Source Code	According to SOAR, the following detection techniques may be useful: Highly cost effective: Source code Weakness Analyzer Context-configured Source Code Weakness Analyzer Effectiveness: High
Architecture or Design Review	According to SOAR, the following detection techniques may be useful: Highly cost effective: Formal Methods / Correct-By-Construction Cost effective for partial coverage: Inspection (IEEE 1028 standard) (can apply to requirements, design, source code, etc.) Effectiveness: High

Affected Resources

File or Directory

Memberships

Nature	Type	ID	Name
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	635	Weaknesses Originally Used by NVD from 2008 to 2016
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	743	CERT C Secure Coding Standard (2008) Chapter 10 - Input Output (FIO)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	751	2009 Top 25 - Insecure Interaction Between Components
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	801	2010 Top 25 - Insecure Interaction Between Components
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	852	The CERT Oracle Secure Coding Standard for Java (2011) Chapter 9 - Visibility and Atomicity (VNA)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	867	2011 Top 25 - Weaknesses On the Cusp
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	877	CERT C++ Secure Coding Section 09 - Input Output (FIO)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	882	CERT C++ Secure Coding Section 14 - Concurrency (CON)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	988	SFP Secondary Cluster: Race Condition Window
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1142	SEI CERT Oracle Secure Coding Standard for Java - Guidelines 08. Visibility and Atomicity (VNA)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1364	ICS Communications: Zone Boundary Failures
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1365	ICS Communications: Unreliability
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1366	ICS Communications: Frail Security in Protocols
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1376	ICS Engineering (Construction/Deployment): Security Gaps in Commissioning
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1387	Weaknesses in the 2022 CWE Top 25 Most Dangerous Software Weaknesses
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1401	Comprehensive Categorization: Concurrency
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1425	Weaknesses in the 2023 CWE Top 25 Most Dangerous Software Weaknesses

Vulnerability Mapping Notes

Usage	ALLOWED-WITH-REVIEW (this CWE ID could be used to map to real-world vulnerabilities in limited situations requiring careful review)
Reason	Abstraction
Rationale	This CWE entry is a Class and might have Base-level children that would be more appropriate
Comments	Examine children of this entry to see if there is a better fit

Notes

Research Gap

Race conditions in web applications are under-studied and probably under-reported. However, in 2008 there has been growing interest in this area.

Research Gap

Much of the focus of race condition research has been in Time-of-check Time-of-use (TOCTOU) variants (CWE-367), but many race conditions are related to synchronization problems that do not necessarily require a time-of-check.

Research Gap

From a classification/taxonomy perspective, the relationships between concurrency and program state need closer investigation and may be useful in organizing related issues.

Maintenance

The relationship between race conditions and synchronization problems (CWE-662) needs to be further developed. They are not necessarily two perspectives of the same core concept, since synchronization is only one technique for avoiding race conditions, and synchronization can be used for other purposes besides race condition prevention.

Taxonomy Mappings

Mapped Taxonomy Name	Node ID	Fit	Mapped Node Name
PLOVER			Race Conditions
The CERT Oracle Secure Coding Standard for Java (2011)	VNA03-J		Do not assume that a group of calls to independently atomic methods is atomic

Related Attack Patterns

CAPEC-ID	Attack Pattern Name
CAPEC-26	Leveraging Race Conditions
CAPEC-29	Leveraging Time-of-Check and Time-of-Use (TOCTOU) Race Conditions

References

[REF-44]	Michael Howard, David LeBlanc and John Viega. "24 Deadly Sins of Software Security". "Sin 13: Race Conditions." Page 205. McGraw-Hill. 2010.
[REF-349]	Andrei Alexandrescu. "volatile - Multithreaded Programmer's Best Friend". Dr. Dobb's. 2008-02-01. <https://drdobbs.com/cpp/volatile-the-multithreaded-programmers-b/184403766>. (URL validated: 2023-04-07)
[REF-350]	Steven Devijver. "Thread-safe webapps using Spring". <https://web.archive.org/web/20170609174845/http://www.javalobby.org/articles/thread-safe/index.jsp>. (URL validated: 2023-04-07)
[REF-351]	David Wheeler. "Prevent race conditions". 2007-10-04. <https://www.ida.liu.se/~TDDC90/literature/papers/SP-race-conditions.pdf>. (URL validated: 2023-04-07)
[REF-352]	Matt Bishop. "Race Conditions, Files, and Security Flaws; or the Tortoise and the Hare Redux". 1995-09. <https://seclab.cs.ucdavis.edu/projects/vulnerabilities/scriv/ucd-ecs-95-08.pdf>. (URL validated: 2023-04-07)
[REF-353]	David Wheeler. "Secure Programming for Linux and Unix HOWTO". 2003-03-03. <https://dwheeler.com/secure-programs/Secure-Programs-HOWTO/avoid-race.html>. (URL validated: 2023-04-07)
[REF-354]	Blake Watts. "Discovering and Exploiting Named Pipe Security Flaws for Fun and Profit". 2002-04. <https://www.blakewatts.com/blog/discovering-and-exploiting-named-pipe-security-flaws-for-fun-and-profit>. (URL validated: 2023-04-07)
[REF-355]	Roberto Paleari, Davide Marrone, Danilo Bruschi and Mattia Monga. "On Race Vulnerabilities in Web Applications". <http://security.dico.unimi.it/~roberto/pubs/dimva08-web.pdf>.
[REF-356]	"Avoiding Race Conditions and Insecure File Operations". Apple Developer Connection. <https://web.archive.org/web/20081010155022/http://developer.apple.com/documentation/Security/Conceptual/SecureCodingGuide/Articles/RaceConditions.html>. (URL validated: 2023-04-07)
[REF-357]	Johannes Ullrich. "Top 25 Series - Rank 25 - Race Conditions". SANS Software Security Institute. 2010-03-26. <https://web.archive.org/web/20100530231203/http://blogs.sans.org:80/appsecstreetfighter/2010/03/26/top-25-series-rank-25-race-conditions/>. (URL validated: 2023-04-07)
[REF-76]	Sean Barnum and Michael Gegick. "Least Privilege". 2005-09-14. <https://web.archive.org/web/20211209014121/https://www.cisa.gov/uscert/bsi/articles/knowledge/principles/least-privilege>. (URL validated: 2023-04-07)
[REF-1237]	CERT Coordination Center. "Intel BIOS locking mechanism contains race condition that enables write protection bypass". 2015-01-05. <https://www.kb.cert.org/vuls/id/766164/>.

Content History

Submissions
Submission Date	Submitter	Organization
2006-07-19 (CWE Draft 3, 2006-07-19)	PLOVER
2006-07-19 (CWE Draft 3, 2006-07-19)
Contributions
Contribution Date	Contributor	Organization
2010-04-30	Martin Sebor	Cisco Systems, Inc.
2010-04-30	Provided Demonstrative Example
2024-02-29 (CWE 4.16, 2024-11-19)	Abhi Balakrishnan
2024-02-29 (CWE 4.16, 2024-11-19)	Provided diagram to improve CWE usability
Modifications
Modification Date	Modifier	Organization
2025-04-03 (CWE 4.17, 2025-04-03)	CWE Content Team	MITRE
2025-04-03 (CWE 4.17, 2025-04-03)	updated Affected_Resources
2024-11-19 (CWE 4.16, 2024-11-19)	CWE Content Team	MITRE
2024-11-19 (CWE 4.16, 2024-11-19)	updated Alternate_Terms, Common_Consequences, Description, Diagram, Modes_of_Introduction
2024-07-16 (CWE 4.15, 2024-07-16)	CWE Content Team	MITRE
2024-07-16 (CWE 4.15, 2024-07-16)	updated Relationships
2023-06-29	CWE Content Team	MITRE
2023-06-29	updated Mapping_Notes, Relationships
2023-04-27	CWE Content Team	MITRE
2023-04-27	updated References, Relationships
2023-01-31	CWE Content Team	MITRE
2023-01-31	updated Applicable_Platforms, Common_Consequences, Description
2022-10-13	CWE Content Team	MITRE
2022-10-13	updated Observed_Examples, References
2022-06-28	CWE Content Team	MITRE
2022-06-28	updated Observed_Examples, Relationships
2022-04-28	CWE Content Team	MITRE
2022-04-28	updated Observed_Examples, Relationships
2021-10-28	CWE Content Team	MITRE
2021-10-28	updated Observed_Examples, References
2021-03-15	CWE Content Team	MITRE
2021-03-15	updated Demonstrative_Examples
2020-08-20	CWE Content Team	MITRE
2020-08-20	updated Relationships
2020-02-24	CWE Content Team	MITRE
2020-02-24	updated Applicable_Platforms, Demonstrative_Examples, Observed_Examples, Relationships
2019-06-20	CWE Content Team	MITRE
2019-06-20	updated Relationships
2019-01-03	CWE Content Team	MITRE
2019-01-03	updated Relationships, Taxonomy_Mappings
2017-11-08	CWE Content Team	MITRE
2017-11-08	updated Demonstrative_Examples, References, Research_Gaps, Taxonomy_Mappings
2015-12-07	CWE Content Team	MITRE
2015-12-07	updated Relationships
2014-07-30	CWE Content Team	MITRE
2014-07-30	updated Detection_Factors, Relationships
2012-05-11	CWE Content Team	MITRE
2012-05-11	updated Potential_Mitigations, References, Relationships
2011-09-13	CWE Content Team	MITRE
2011-09-13	updated Relationships, Taxonomy_Mappings
2011-06-27	CWE Content Team	MITRE
2011-06-27	updated Relationships
2011-06-01	CWE Content Team	MITRE
2011-06-01	updated Common_Consequences, Relationships, Taxonomy_Mappings
2010-12-13	CWE Content Team	MITRE
2010-12-13	updated Applicable_Platforms, Demonstrative_Examples, Description, Name, Potential_Mitigations, Relationships
2010-09-27	CWE Content Team	MITRE
2010-09-27	updated Observed_Examples, Potential_Mitigations, Relationships
2010-06-21	CWE Content Team	MITRE
2010-06-21	updated Common_Consequences, Demonstrative_Examples, Detection_Factors, Potential_Mitigations, References
2010-02-16	CWE Content Team	MITRE
2010-02-16	updated Detection_Factors, References, Relationships
2009-05-27	CWE Content Team	MITRE
2009-05-27	updated Relationships
2009-03-10	CWE Content Team	MITRE
2009-03-10	updated Demonstrative_Examples, Potential_Mitigations
2009-01-12	CWE Content Team	MITRE
2009-01-12	updated Applicable_Platforms, Common_Consequences, Demonstrative_Examples, Description, Likelihood_of_Exploit, Maintenance_Notes, Observed_Examples, Potential_Mitigations, References, Relationships, Research_Gaps
2008-11-24	CWE Content Team	MITRE
2008-11-24	updated Relationships, Taxonomy_Mappings
2008-10-14	CWE Content Team	MITRE
2008-10-14	updated Relationships
2008-09-08	CWE Content Team	MITRE
2008-09-08	updated Relationships, Taxonomy_Mappings
2008-07-01	Eric Dalci	Cigital
2008-07-01	updated Time_of_Introduction
Previous Entry Names
Change Date	Previous Entry Name
2008-04-11	Race Conditions
2010-12-13	Race Condition

Weakness ID: 390

View customized information:

Description

The product detects a specific error, but takes no actions to handle the error.

Common Consequences

Impact	Details
Varies by Context; Unexpected State; Alter Execution Logic	Scope: Integrity, Other An attacker could utilize an ignored error condition to place the system in an unexpected state that could lead to the execution of unintended logic and could cause other unintended behavior.

Potential Mitigations

Phase(s)	Mitigation
Implementation	Properly handle each exception. This is the recommended solution. Ensure that all exceptions are handled in such a way that you can be sure of the state of your system at any given moment.
Implementation	If a function returns an error, it is important to either fix the problem and try again, alert the user that an error has happened and let the program continue, or alert the user and close and cleanup the program.
Testing	Subject the product to extensive testing to discover some of the possible instances of where/how errors or return values are not handled. Consider testing techniques such as ad hoc, equivalence partitioning, robustness and fault tolerance, mutation, and fuzzing.

Relationships

Relevant to the view "Research Concepts" (View-1000)

Nature	Type	ID	Name
ChildOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	755	Improper Handling of Exceptional Conditions
PeerOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	600	Uncaught Exception in Servlet
CanPrecede	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	401	Missing Release of Memory after Effective Lifetime

Relevant to the view "Software Development" (View-699)

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	389	Error Conditions, Return Values, Status Codes

Relevant to the view "Architectural Concepts" (View-1008)

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1020	Verify Message Integrity

Modes Of Introduction

Phase	Note
Implementation	REALIZATION: This weakness is caused during implementation of an architectural security tactic.

Applicable Platforms

Languages

Class: Not Language-Specific (Undetermined Prevalence)

Likelihood Of Exploit

Medium

Demonstrative Examples

Example 1

The following example attempts to allocate memory for a character. After the call to malloc, an if statement is used to check whether the malloc function failed.

(bad code)

Example Language: C

foo=malloc(sizeof(char)); //the next line checks to see if malloc failed
if (foo==NULL) {

//We do nothing so we just ignore the error.

}

The conditional successfully detects a NULL return value from malloc indicating a failure, however it does not do anything to handle the problem. Unhandled errors may have unexpected results and may cause the program to crash or terminate.

Instead, the if block should contain statements that either attempt to fix the problem or notify the user that an error has occurred and continue processing or perform some cleanup and gracefully terminate the program. The following example notifies the user that the malloc function did not allocate the required memory resources and returns an error code.

(good code)

Example Language: C

foo=malloc(sizeof(char)); //the next line checks to see if malloc failed
if (foo==NULL) {

printf("Malloc failed to allocate memory resources");
return -1;

}

Example 2

In the following C++ example the method readFile() will read the file whose name is provided in the input parameter and will return the contents of the file in char string. The method calls open() and read() may result in errors if the file does not exist or does not contain any data to read. These errors will be thrown when the is_open() method and good() method indicate errors opening or reading the file. However, these errors are not handled within the catch statement. Catch statements that do not perform any processing will have unexpected results. In this case an empty char string will be returned, and the file will not be properly closed.

(bad code)

Example Language: C++

char* readfile (char *filename) {

try {

// open input file
ifstream infile;
infile.open(filename);

if (!infile.is_open()) {

throw "Unable to open file " + filename;

}

// get length of file
infile.seekg (0, ios::end);
int length = infile.tellg();
infile.seekg (0, ios::beg);

// allocate memory
char *buffer = new char [length];

// read data from file
infile.read (buffer,length);

if (!infile.good()) {

throw "Unable to read from file " + filename;

}

infile.close();

return buffer;

}
catch (...) {

/* bug: insert code to handle this later */

}

The catch statement should contain statements that either attempt to fix the problem or notify the user that an error has occurred and continue processing or perform some cleanup and gracefully terminate the program. The following C++ example contains two catch statements. The first of these will catch a specific error thrown within the try block, and the second catch statement will catch all other errors from within the catch block. Both catch statements will notify the user that an error has occurred, close the file, and rethrow to the block that called the readFile() method for further handling or possible termination of the program.

(good code)

Example Language: C++

char* readFile (char *filename) {

try {

// open input file
ifstream infile;
infile.open(filename);

if (!infile.is_open()) {

throw "Unable to open file " + filename;

throw "Unable to read from file " + filename;

}
infile.close();

return buffer;

}
catch (char *str) {

printf("Error: %s \n", str);
infile.close();
throw str;

}
catch (...) {

printf("Error occurred trying to read from file \n");
infile.close();
throw;

}

Example 3

In the following Java example the method readFile will read the file whose name is provided in the input parameter and will return the contents of the file in a String object. The constructor of the FileReader object and the read method call may throw exceptions and therefore must be within a try/catch block. While the catch statement in this example will catch thrown exceptions in order for the method to compile, no processing is performed to handle the thrown exceptions. Catch statements that do not perform any processing will have unexpected results. In this case, this will result in the return of a null String.

(bad code)

Example Language: Java

public String readFile(String filename) {

String retString = null;
try {

// initialize File and FileReader objects
File file = new File(filename);
FileReader fr = new FileReader(file);

// initialize character buffer
long fLen = file.length();
char[] cBuf = new char[(int) fLen];

// read data from file
int iRead = fr.read(cBuf, 0, (int) fLen);

// close file
fr.close();

retString = new String(cBuf);

} catch (Exception ex) {

/* do nothing, but catch so it'll compile... */

}
return retString;

}

The catch statement should contain statements that either attempt to fix the problem, notify the user that an exception has been raised and continue processing, or perform some cleanup and gracefully terminate the program. The following Java example contains three catch statements. The first of these will catch the FileNotFoundException that may be thrown by the FileReader constructor called within the try/catch block. The second catch statement will catch the IOException that may be thrown by the read method called within the try/catch block. The third catch statement will catch all other exceptions thrown within the try block. For all catch statements the user is notified that the exception has been thrown and the exception is rethrown to the block that called the readFile() method for further processing or possible termination of the program. Note that with Java it is usually good practice to use the getMessage() method of the exception class to provide more information to the user about the exception raised.

(good code)

Example Language: Java

public String readFile(String filename) throws FileNotFoundException, IOException, Exception {

String retString = null;
try {

// initialize File and FileReader objects
File file = new File(filename);
FileReader fr = new FileReader(file);

// initialize character buffer
long fLen = file.length();
char [] cBuf = new char[(int) fLen];

// read data from file
int iRead = fr.read(cBuf, 0, (int) fLen);

// close file
fr.close();

retString = new String(cBuf);

} catch (FileNotFoundException ex) {

System.err.println ("Error: FileNotFoundException opening the input file: " + filename );
System.err.println ("" + ex.getMessage() );
throw new FileNotFoundException(ex.getMessage());

} catch (IOException ex) {

System.err.println("Error: IOException reading the input file.\n" + ex.getMessage() );
throw new IOException(ex);

} catch (Exception ex) {

System.err.println("Error: Exception reading the input file.\n" + ex.getMessage() );
throw new Exception(ex);

}
return retString;

}

Selected Observed Examples

Reference	Description
CVE-2022-21820	A GPU data center manager detects an error due to a malformed request but does not act on it, leading to memory corruption.

Detection Methods

Method

Details

Automated Static Analysis

Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)

Effectiveness: High

Memberships

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	728	OWASP Top Ten 2004 Category A7 - Improper Error Handling
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	851	The CERT Oracle Secure Coding Standard for Java (2011) Chapter 8 - Exceptional Behavior (ERR)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	880	CERT C++ Secure Coding Section 12 - Exceptions and Error Handling (ERR)
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	884	CWE Cross-section
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	962	SFP Secondary Cluster: Unchecked Status Condition
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1306	CISQ Quality Measures - Reliability
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1405	Comprehensive Categorization: Improper Check or Handling of Exceptional Conditions

Vulnerability Mapping Notes

Usage	ALLOWED (this CWE ID may be used to map to real-world vulnerabilities)
Reason	Acceptable-Use
Rationale	This CWE entry is at the Base level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.
Comments	Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction.

Taxonomy Mappings

Mapped Taxonomy Name	Node ID	Mapped Node Name
CLASP		Improper error handling
The CERT Oracle Secure Coding Standard for Java (2011)	ERR00-J	Do not suppress or ignore checked exceptions
Software Fault Patterns	SFP4	Unchecked Status Condition

References

[REF-18]	Secure Software, Inc.. "The CLASP Application Security Process". 2005. <https://cwe.mitre.org/documents/sources/TheCLASPApplicationSecurityProcess.pdf>. (URL validated: 2024-11-17)
[REF-44]	Michael Howard, David LeBlanc and John Viega. "24 Deadly Sins of Software Security". "Sin 11: Failure to Handle Errors Correctly." Page 183. McGraw-Hill. 2010.

Content History

Submissions
Submission Date	Submitter	Organization
2006-07-19 (CWE Draft 3, 2006-07-19)	CLASP
2006-07-19 (CWE Draft 3, 2006-07-19)
Modifications
Modification Date	Modifier	Organization
2024-02-29 (CWE 4.14, 2024-02-29)	CWE Content Team	MITRE
2024-02-29 (CWE 4.14, 2024-02-29)	updated Demonstrative_Examples
2023-10-26	CWE Content Team	MITRE
2023-10-26	updated Observed_Examples
2023-06-29	CWE Content Team	MITRE
2023-06-29	updated Mapping_Notes
2023-04-27	CWE Content Team	MITRE
2023-04-27	updated Detection_Factors, Relationships, Time_of_Introduction
2023-01-31	CWE Content Team	MITRE
2023-01-31	updated Description, Potential_Mitigations
2020-08-20	CWE Content Team	MITRE
2020-08-20	updated Relationships
2020-02-24	CWE Content Team	MITRE
2020-02-24	updated References, Type
2019-01-03	CWE Content Team	MITRE
2019-01-03	updated Related_Attack_Patterns, Taxonomy_Mappings
2017-11-08	CWE Content Team	MITRE
2017-11-08	updated Applicable_Platforms, Modes_of_Introduction, Relationships, Taxonomy_Mappings
2014-07-30	CWE Content Team	MITRE
2014-07-30	updated Relationships, Taxonomy_Mappings
2014-02-18	CWE Content Team	MITRE
2014-02-18	updated Related_Attack_Patterns
2012-05-11	CWE Content Team	MITRE
2012-05-11	updated Common_Consequences, References, Relationships
2011-09-13	CWE Content Team	MITRE
2011-09-13	updated Relationships, Taxonomy_Mappings
2011-06-27	CWE Content Team	MITRE
2011-06-27	updated Common_Consequences
2011-06-01	CWE Content Team	MITRE
2011-06-01	updated Common_Consequences, Relationships, Taxonomy_Mappings
2009-07-27	CWE Content Team	MITRE
2009-07-27	updated Demonstrative_Examples
2009-03-10	CWE Content Team	MITRE
2009-03-10	updated Relationships
2008-11-24	CWE Content Team	MITRE
2008-11-24	updated Demonstrative_Examples, Description, Other_Notes, Potential_Mitigations
2008-09-08	CWE Content Team	MITRE
2008-09-08	updated Relationships, Other_Notes, Taxonomy_Mappings
2008-07-01	Eric Dalci	Cigital
2008-07-01	updated Time_of_Introduction
Previous Entry Names
Change Date	Previous Entry Name
2008-04-11	Improper Error Handling

Weakness ID: 73

View customized information:

Description

The product allows user input to control or influence paths or file names that are used in filesystem operations.

Extended Description

This could allow an attacker to access or modify system files or other files that are critical to the application.

Path manipulation errors occur when the following two conditions are met:

1. An attacker can specify a path used in an operation on the filesystem.

2. By specifying the resource, the attacker gains a capability that would not otherwise be permitted.

For example, the program may give the attacker the ability to overwrite the specified file or run with a configuration controlled by the attacker.

Common Consequences

Impact	Details
Read Files or Directories; Modify Files or Directories	Scope: Integrity, Confidentiality The application can operate on unexpected files. Confidentiality is violated when the targeted filename is not directly readable by the attacker.
Modify Files or Directories; Execute Unauthorized Code or Commands	Scope: Integrity, Confidentiality, Availability The application can operate on unexpected files. This may violate integrity if the filename is written to, or if the filename is for a program or other form of executable code.
DoS: Crash, Exit, or Restart; DoS: Resource Consumption (Other)	Scope: Availability The application can operate on unexpected files. Availability can be violated if the attacker specifies an unexpected file that the application modifies. Availability can also be affected if the attacker specifies a filename for a large file, or points to a special device or a file that does not have the format that the application expects.

Potential Mitigations

Phase(s)	Mitigation
Architecture and Design	When the set of filenames is limited or known, create a mapping from a set of fixed input values (such as numeric IDs) to the actual filenames, and reject all other inputs. For example, ID 1 could map to "inbox.txt" and ID 2 could map to "profile.txt". Features such as the ESAPI AccessReferenceMap provide this capability.
Architecture and Design; Operation	Run your code in a "jail" or similar sandbox environment that enforces strict boundaries between the process and the operating system. This may effectively restrict all access to files within a particular directory. Examples include the Unix chroot jail and AppArmor. In general, managed code may provide some protection. This may not be a feasible solution, and it only limits the impact to the operating system; the rest of your application may still be subject to compromise. Be careful to avoid CWE-243 and other weaknesses related to jails.
Architecture and Design	For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.
Implementation	Strategy: Input Validation Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does. When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue." Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright. When validating filenames, use stringent allowlists that limit the character set to be used. If feasible, only allow a single "." character in the filename to avoid weaknesses such as CWE-23, and exclude directory separators such as "/" to avoid CWE-36. Use a list of allowable file extensions, which will help to avoid CWE-434. Do not rely exclusively on a filtering mechanism that removes potentially dangerous characters. This is equivalent to a denylist, which may be incomplete (CWE-184). For example, filtering "/" is insufficient protection if the filesystem also supports the use of "\" as a directory separator. Another possible error could occur when the filtering is applied in a way that still produces dangerous data (CWE-182). For example, if "../" sequences are removed from the ".../...//" string in a sequential fashion, two instances of "../" would be removed from the original string, but the remaining characters would still form the "../" string. Effectiveness: High
Implementation	Use a built-in path canonicalization function (such as realpath() in C) that produces the canonical version of the pathname, which effectively removes ".." sequences and symbolic links (CWE-23, CWE-59).
Installation; Operation	Use OS-level permissions and run as a low-privileged user to limit the scope of any successful attack.
Operation; Implementation	If you are using PHP, configure your application so that it does not use register_globals. During implementation, develop your application so that it does not rely on this feature, but be wary of implementing a register_globals emulation that is subject to weaknesses such as CWE-95, CWE-621, and similar issues.
Testing	Use tools and techniques that require manual (human) analysis, such as penetration testing, threat modeling, and interactive tools that allow the tester to record and modify an active session. These may be more effective than strictly automated techniques. This is especially the case with weaknesses that are related to design and business rules.

Relationships

Relevant to the view "Research Concepts" (View-1000)

Nature	Type	ID	Name
ChildOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	610	Externally Controlled Reference to a Resource in Another Sphere
ChildOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	642	External Control of Critical State Data
ParentOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	114	Process Control
CanPrecede	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	22	Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
CanPrecede	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	41	Improper Resolution of Path Equivalence
CanPrecede	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	59	Improper Link Resolution Before File Access ('Link Following')
CanPrecede	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	98	Improper Control of Filename for Include/Require Statement in PHP Program ('PHP Remote File Inclusion')
CanPrecede	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	434	Unrestricted Upload of File with Dangerous Type

Relevant to the view "Software Development" (View-699)

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	399	Resource Management Errors

Relevant to the view "Architectural Concepts" (View-1008)

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1015	Limit Access

Relevant to the view "Seven Pernicious Kingdoms" (View-700)

Nature	Type	ID	Name
ChildOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	20	Improper Input Validation

Modes Of Introduction

Phase	Note
Architecture and Design
Implementation	REALIZATION: This weakness is caused during implementation of an architectural security tactic.

Applicable Platforms

Languages	Class: Not Language-Specific (Undetermined Prevalence)
Operating Systems	Class: Unix (Often Prevalent) Class: Windows (Often Prevalent) Class: macOS (Often Prevalent)

Likelihood Of Exploit

High

Demonstrative Examples

Example 1

The following code uses input from an HTTP request to create a file name. The programmer has not considered the possibility that an attacker could provide a file name such as "../../tomcat/conf/server.xml", which causes the application to delete one of its own configuration files (CWE-22).

(bad code)

Example Language: Java

String rName = request.getParameter("reportName");
File rFile = new File("/usr/local/apfr/reports/" + rName);
...
rFile.delete();

Example 2

The following code uses input from a configuration file to determine which file to open and echo back to the user. If the program runs with privileges and malicious users can change the configuration file, they can use the program to read any file on the system that ends with the extension .txt.

(bad code)

Example Language: Java

fis = new FileInputStream(cfg.getProperty("sub")+".txt");
amt = fis.read(arr);
out.println(arr);

Selected Observed Examples

Reference	Description
CVE-2022-45918	Chain: a learning management tool debugger uses external input to locate previous session logs (CWE-73) and does not properly validate the given path (CWE-20), allowing for filesystem path traversal using "../" sequences (CWE-24)
CVE-2008-5748	Chain: external control of values for user's desired language and theme enables path traversal.
CVE-2008-5764	Chain: external control of user's target language enables remote file inclusion.

Weakness Ordinalities

Ordinality	Description
Primary	(where the weakness exists independent of other weaknesses)

Detection Methods

Method	Details
Automated Static Analysis	The external control or influence of filenames can often be detected using automated static analysis that models data flow within the product. Automated static analysis might not be able to recognize when proper input validation is being performed, leading to false positives - i.e., warnings that do not have any security consequences or require any code changes.

Memberships

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	723	OWASP Top Ten 2004 Category A2 - Broken Access Control
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	752	2009 Top 25 - Risky Resource Management
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	877	CERT C++ Secure Coding Section 09 - Input Output (FIO)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	981	SFP Secondary Cluster: Path Traversal
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1348	OWASP Top Ten 2021 Category A04:2021 - Insecure Design
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1403	Comprehensive Categorization: Exposed Resource

Vulnerability Mapping Notes

Usage	ALLOWED (this CWE ID may be used to map to real-world vulnerabilities)
Reason	Acceptable-Use
Rationale	This CWE entry is at the Base level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.
Comments	Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction.

Notes

Relationship

The external control of filenames can be the primary link in chains with other file-related weaknesses, as seen in the CanPrecede relationships. This is because software systems use files for many different purposes: to execute programs, load code libraries, to store application data, to store configuration settings, record temporary data, act as signals or semaphores to other processes, etc.

However, those weaknesses do not always require external control. For example, link-following weaknesses (CWE-59) often involve pathnames that are not controllable by the attacker at all.

The external control can be resultant from other issues. For example, in PHP applications, the register_globals setting can allow an attacker to modify variables that the programmer thought were immutable, enabling file inclusion (CWE-98) and path traversal (CWE-22). Operating with excessive privileges (CWE-250) might allow an attacker to specify an input filename that is not directly readable by the attacker, but is accessible to the privileged program. A buffer overflow (CWE-119) might give an attacker control over nearby memory locations that are related to pathnames, but were not directly modifiable by the attacker.

Maintenance

CWE-114 is a Class, but it is listed a child of CWE-73 in view 1000. This suggests some abstraction problems that should be resolved in future versions.

Taxonomy Mappings

Mapped Taxonomy Name	Node ID	Fit	Mapped Node Name
7 Pernicious Kingdoms			Path Manipulation
Software Fault Patterns	SFP16		Path Traversal

Related Attack Patterns

CAPEC-ID	Attack Pattern Name
CAPEC-13	Subverting Environment Variable Values
CAPEC-267	Leverage Alternate Encoding
CAPEC-64	Using Slashes and URL Encoding Combined to Bypass Validation Logic
CAPEC-72	URL Encoding
CAPEC-76	Manipulating Web Input to File System Calls
CAPEC-78	Using Escaped Slashes in Alternate Encoding
CAPEC-79	Using Slashes in Alternate Encoding
CAPEC-80	Using UTF-8 Encoding to Bypass Validation Logic

References

[REF-6]	Katrina Tsipenyuk, Brian Chess and Gary McGraw. "Seven Pernicious Kingdoms: A Taxonomy of Software Security Errors". NIST Workshop on Software Security Assurance Tools Techniques and Metrics. NIST. 2005-11-07. <https://samate.nist.gov/SSATTM_Content/papers/Seven%20Pernicious%20Kingdoms%20-%20Taxonomy%20of%20Sw%20Security%20Errors%20-%20Tsipenyuk%20-%20Chess%20-%20McGraw.pdf>.
[REF-45]	OWASP. "OWASP Enterprise Security API (ESAPI) Project". <http://www.owasp.org/index.php/ESAPI>.

Content History

Submissions
Submission Date	Submitter	Organization
2006-07-19 (CWE Draft 3, 2006-07-19)	7 Pernicious Kingdoms
2006-07-19 (CWE Draft 3, 2006-07-19)
Modifications
Modification Date	Modifier	Organization
2023-10-26	CWE Content Team	MITRE
2023-10-26	updated Observed_Examples
2023-06-29	CWE Content Team	MITRE
2023-06-29	updated Mapping_Notes
2023-04-27	CWE Content Team	MITRE
2023-04-27	updated Potential_Mitigations, Relationships
2023-01-31	CWE Content Team	MITRE
2023-01-31	updated Description, Detection_Factors, Potential_Mitigations
2021-10-28	CWE Content Team	MITRE
2021-10-28	updated Relationships
2021-03-15	CWE Content Team	MITRE
2021-03-15	updated Maintenance_Notes, Potential_Mitigations
2020-06-25	CWE Content Team	MITRE
2020-06-25	updated Potential_Mitigations, Relationships
2020-02-24	CWE Content Team	MITRE
2020-02-24	updated Potential_Mitigations, References, Relationships, Time_of_Introduction, Type
2017-11-08	CWE Content Team	MITRE
2017-11-08	updated Applicable_Platforms, Likelihood_of_Exploit, Modes_of_Introduction, Relationships, Taxonomy_Mappings
2014-07-30	CWE Content Team	MITRE
2014-07-30	updated Relationships, Taxonomy_Mappings
2012-10-30	CWE Content Team	MITRE
2012-10-30	updated Potential_Mitigations
2012-05-11	CWE Content Team	MITRE
2012-05-11	updated Demonstrative_Examples, References, Related_Attack_Patterns, Relationships, Taxonomy_Mappings
2011-09-13	CWE Content Team	MITRE
2011-09-13	updated Relationships, Taxonomy_Mappings
2011-06-01	CWE Content Team	MITRE
2011-06-01	updated Common_Consequences, Relationships, Taxonomy_Mappings
2010-02-16	CWE Content Team	MITRE
2010-02-16	updated Potential_Mitigations
2009-12-28	CWE Content Team	MITRE
2009-12-28	updated Detection_Factors
2009-10-29	CWE Content Team	MITRE
2009-10-29	updated Common_Consequences, Description
2009-07-27	CWE Content Team	MITRE
2009-07-27	updated Demonstrative_Examples
2009-03-10	CWE Content Team	MITRE
2009-03-10	updated Potential_Mitigations, Relationships
2009-01-12	CWE Content Team	MITRE
2009-01-12	updated Applicable_Platforms, Causal_Nature, Common_Consequences, Demonstrative_Examples, Description, Observed_Examples, Other_Notes, Potential_Mitigations, References, Relationship_Notes, Relationships, Weakness_Ordinalities
2008-09-08	CWE Content Team	MITRE
2008-09-08	updated Relationships, Other_Notes, Taxonomy_Mappings, Weakness_Ordinalities
2008-07-01	Eric Dalci	Cigital
2008-07-01	updated Time_of_Introduction
Previous Entry Names
Change Date	Previous Entry Name
2008-04-11	Path Manipulation

Weakness ID: 209

View customized information:

Description

The product generates an error message that includes sensitive information about its environment, users, or associated data.

Extended Description

The sensitive information may be valuable information on its own (such as a password), or it may be useful for launching other, more serious attacks. The error message may be created in different ways:

self-generated: the source code explicitly constructs the error message and delivers it
externally-generated: the external environment, such as a language interpreter, handles the error and constructs its own message, whose contents are not under direct control by the programmer

An attacker may use the contents of error messages to help launch another, more focused attack. For example, an attempt to exploit a path traversal weakness (CWE-22) might yield the full pathname of the installed application. In turn, this could be used to select the proper number of ".." sequences to navigate to the targeted file. An attack using SQL injection (CWE-89) might not initially succeed, but an error message could reveal the malformed query, which would expose query logic and possibly even passwords or other sensitive information used within the query.

Common Consequences

Impact	Details
Read Application Data	Scope: Confidentiality Often this will either reveal sensitive information which may be used for a later attack or private information stored in the server.

Potential Mitigations

Phase(s)	Mitigation
Implementation	Ensure that error messages only contain minimal details that are useful to the intended audience and no one else. The messages need to strike the balance between being too cryptic (which can confuse users) or being too detailed (which may reveal more than intended). The messages should not reveal the methods that were used to determine the error. Attackers can use detailed information to refine or optimize their original attack, thereby increasing their chances of success. If errors must be captured in some detail, record them in log messages, but consider what could occur if the log messages can be viewed by attackers. Highly sensitive information such as passwords should never be saved to log files. Avoid inconsistent messaging that might accidentally tip off an attacker about internal state, such as whether a user account exists or not.
Implementation	Handle exceptions internally and do not display errors containing potentially sensitive information to a user.
Implementation	Strategy: Attack Surface Reduction Use naming conventions and strong types to make it easier to spot when sensitive data is being used. When creating structures, objects, or other complex entities, separate the sensitive and non-sensitive data as much as possible. Effectiveness: Defense in Depth Note: This makes it easier to spot places in the code where data is being used that is unencrypted.
Implementation; Build and Compilation	Strategy: Compilation or Build Hardening Debugging information should not make its way into a production release.
Implementation; Build and Compilation	Strategy: Environment Hardening Debugging information should not make its way into a production release.
System Configuration	Where available, configure the environment to use less verbose error messages. For example, in PHP, disable the display_errors setting during configuration, or at runtime using the error_reporting() function.
System Configuration	Create default error pages or messages that do not leak any information.

Relationships

Relevant to the view "Research Concepts" (View-1000)

Nature	Type	ID	Name
ChildOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	200	Exposure of Sensitive Information to an Unauthorized Actor
ChildOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	755	Improper Handling of Exceptional Conditions
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	210	Self-generated Error Message Containing Sensitive Information
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	211	Externally-Generated Error Message Containing Sensitive Information
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	550	Server-generated Error Message Containing Sensitive Information
PeerOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	1295	Debug Messages Revealing Unnecessary Information
CanFollow	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	600	Uncaught Exception in Servlet
CanFollow	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	756	Missing Custom Error Page

Relevant to the view "Software Development" (View-699)

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	199	Information Management Errors
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	389	Error Conditions, Return Values, Status Codes

Relevant to the view "Weaknesses for Simplified Mapping of Published Vulnerabilities" (View-1003)

Nature	Type	ID	Name
ChildOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	200	Exposure of Sensitive Information to an Unauthorized Actor

Relevant to the view "Architectural Concepts" (View-1008)

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1015	Limit Access

Modes Of Introduction

Phase	Note
Architecture and Design
Implementation	REALIZATION: This weakness is caused during implementation of an architectural security tactic.
System Configuration
Operation

Applicable Platforms

Languages

PHP (Often Prevalent)

Java (Often Prevalent)

Class: Not Language-Specific (Undetermined Prevalence)

Likelihood Of Exploit

High

Demonstrative Examples

Example 1

In the following example, sensitive information might be printed depending on the exception that occurs.

(bad code)

Example Language: Java

try {

/.../

}
catch (Exception e) {

System.out.println(e);

}

If an exception related to SQL is handled by the catch, then the output might contain sensitive information such as SQL query structure or private information. If this output is redirected to a web user, this may represent a security problem.

Example 2

This code tries to open a database connection, and prints any exceptions that occur.

(bad code)

Example Language: PHP

try {

openDbConnection();

}
//print exception message that includes exception message and configuration file location
catch (Exception $e) {

echo 'Caught exception: ', $e->getMessage(), '\n';
echo 'Check credentials in config file at: ', $Mysql_config_location, '\n';

}

If an exception occurs, the printed message exposes the location of the configuration file the script is using. An attacker can use this information to target the configuration file (perhaps exploiting a Path Traversal weakness). If the file can be read, the attacker could gain credentials for accessing the database. The attacker may also be able to replace the file with a malicious one, causing the application to use an arbitrary database.

Example 3

The following code generates an error message that leaks the full pathname of the configuration file.

(bad code)

Example Language: Perl

$ConfigDir = "/home/myprog/config";
$uname = GetUserInput("username");

# avoid CWE-22, CWE-78, others.
ExitError("Bad hacker!") if ($uname !~ /^\w+$/);
$file = "$ConfigDir/$uname.txt";
if (! (-e $file)) {

ExitError("Error: $file does not exist");

}
...

If this code is running on a server, such as a web application, then the person making the request should not know what the full pathname of the configuration directory is. By submitting a username that does not produce a $file that exists, an attacker could get this pathname. It could then be used to exploit path traversal or symbolic link following problems that may exist elsewhere in the application.

Example 4

In the example below, the method getUserBankAccount retrieves a bank account object from a database using the supplied username and account number to query the database. If an SQLException is raised when querying the database, an error message is created and output to a log file.

(bad code)

Example Language: Java

public BankAccount getUserBankAccount(String username, String accountNumber) {

BankAccount userAccount = null;
String query = null;
try {

if (isAuthorizedUser(username)) {

query = "SELECT * FROM accounts WHERE owner = "
+ username + " AND accountID = " + accountNumber;
DatabaseManager dbManager = new DatabaseManager();
Connection conn = dbManager.getConnection();
Statement stmt = conn.createStatement();
ResultSet queryResult = stmt.executeQuery(query);
userAccount = (BankAccount)queryResult.getObject(accountNumber);

}

} catch (SQLException ex) {

String logMessage = "Unable to retrieve account information from database,\nquery: " + query;
Logger.getLogger(BankManager.class.getName()).log(Level.SEVERE, logMessage, ex);

}
return userAccount;

}

The error message that is created includes information about the database query that may contain sensitive information about the database or query logic. In this case, the error message will expose the table name and column names used in the database. This data could be used to simplify other attacks, such as SQL injection (CWE-89) to directly access the database.

Selected Observed Examples

Reference	Description
CVE-2008-2049	POP3 server reveals a password in an error message after multiple APOP commands are sent. Might be resultant from another weakness.
CVE-2007-5172	Program reveals password in error message if attacker can trigger certain database errors.
CVE-2008-4638	Composite: application running with high privileges (CWE-250) allows user to specify a restricted file to process, which generates a parsing error that leaks the contents of the file (CWE-209).
CVE-2008-1579	Existence of user names can be determined by requesting a nonexistent blog and reading the error message.
CVE-2007-1409	Direct request to library file in web application triggers pathname leak in error message.
CVE-2008-3060	Malformed input to login page causes leak of full path when IMAP call fails.
CVE-2005-0603	Malformed regexp syntax leads to information exposure in error message.
CVE-2017-9615	verbose logging stores admin credentials in a world-readablelog file
CVE-2018-1999036	SSH password for private key stored in build log

Weakness Ordinalities

Ordinality	Description
Primary	(where the weakness exists independent of other weaknesses)
Resultant	(where the weakness is typically related to the presence of some other weaknesses)

Detection Methods

Method	Details
Manual Analysis	This weakness generally requires domain-specific interpretation using manual analysis. However, the number of potential error conditions may be too large to cover completely within limited time constraints. Effectiveness: High
Automated Analysis	Automated methods may be able to detect certain idioms automatically, such as exposed stack traces or pathnames, but violation of business rules or privacy requirements is not typically feasible. Effectiveness: Moderate
Automated Dynamic Analysis	This weakness can be detected using dynamic tools and techniques that interact with the software using large test suites with many diverse inputs, such as fuzz testing (fuzzing), robustness testing, and fault injection. The software's operation may slow down, but it should not become unstable, crash, or generate incorrect results. Error conditions may be triggered with a stress-test by calling the software simultaneously from a large number of threads or processes, and look for evidence of any unexpected behavior. Effectiveness: Moderate
Manual Dynamic Analysis	Identify error conditions that are not likely to occur during normal usage and trigger them. For example, run the program under low memory conditions, run with insufficient privileges or permissions, interrupt a transaction before it is completed, or disable connectivity to basic network services such as DNS. Monitor the software for any unexpected behavior. If you trigger an unhandled exception or similar error that was discovered and handled by the application's environment, it may still indicate unexpected conditions that were not handled by the application itself.
Automated Static Analysis	Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)

Memberships

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	717	OWASP Top Ten 2007 Category A6 - Information Leakage and Improper Error Handling
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	728	OWASP Top Ten 2004 Category A7 - Improper Error Handling
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	731	OWASP Top Ten 2004 Category A10 - Insecure Configuration Management
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	751	2009 Top 25 - Insecure Interaction Between Components
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	801	2010 Top 25 - Insecure Interaction Between Components
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	815	OWASP Top Ten 2010 Category A6 - Security Misconfiguration
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	851	The CERT Oracle Secure Coding Standard for Java (2011) Chapter 8 - Exceptional Behavior (ERR)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	867	2011 Top 25 - Weaknesses On the Cusp
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	880	CERT C++ Secure Coding Section 12 - Exceptions and Error Handling (ERR)
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	884	CWE Cross-section
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	933	OWASP Top Ten 2013 Category A5 - Security Misconfiguration
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	963	SFP Secondary Cluster: Exposed Data
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1032	OWASP Top Ten 2017 Category A6 - Security Misconfiguration
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1348	OWASP Top Ten 2021 Category A04:2021 - Insecure Design
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1417	Comprehensive Categorization: Sensitive Information Exposure

Vulnerability Mapping Notes

Usage	ALLOWED (this CWE ID may be used to map to real-world vulnerabilities)
Reason	Acceptable-Use
Rationale	This CWE entry is at the Base level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.
Comments	Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction.

Taxonomy Mappings

Mapped Taxonomy Name	Node ID	Fit	Mapped Node Name
CLASP			Accidental leaking of sensitive information through error messages
OWASP Top Ten 2007	A6	CWE More Specific	Information Leakage and Improper Error Handling
OWASP Top Ten 2004	A7	CWE More Specific	Improper Error Handling
OWASP Top Ten 2004	A10	CWE More Specific	Insecure Configuration Management
The CERT Oracle Secure Coding Standard for Java (2011)	ERR01-J		Do not allow exceptions to expose sensitive information
Software Fault Patterns	SFP23		Exposed Data

Related Attack Patterns

CAPEC-ID	Attack Pattern Name
CAPEC-215	Fuzzing for application mapping
CAPEC-463	Padding Oracle Crypto Attack
CAPEC-54	Query System for Information
CAPEC-7	Blind SQL Injection

References

[REF-174]	Web Application Security Consortium. "Information Leakage". <http://projects.webappsec.org/w/page/13246936/Information%20Leakage>. (URL validated: 2023-04-07)
[REF-175]	Brian Chess and Jacob West. "Secure Programming with Static Analysis". Section 9.2, Page 326. Addison-Wesley. 2007.
[REF-176]	Michael Howard and David LeBlanc. "Writing Secure Code". Chapter 16, "General Good Practices." Page 415. 1st Edition. Microsoft Press. 2001-11-13.
[REF-44]	Michael Howard, David LeBlanc and John Viega. "24 Deadly Sins of Software Security". "Sin 11: Failure to Handle Errors Correctly." Page 183. McGraw-Hill. 2010.
[REF-44]	Michael Howard, David LeBlanc and John Viega. "24 Deadly Sins of Software Security". "Sin 12: Information Leakage." Page 191. McGraw-Hill. 2010.
[REF-179]	Johannes Ullrich. "Top 25 Series - Rank 16 - Information Exposure Through an Error Message". SANS Software Security Institute. 2010-03-17. <http://software-security.sans.org/blog/2010/03/17/top-25-series-rank-16-information-exposure-through-an-error-message>.
[REF-62]	Mark Dowd, John McDonald and Justin Schuh. "The Art of Software Security Assessment". Chapter 3, "Overly Verbose Error Messages", Page 75. 1st Edition. Addison Wesley. 2006.
[REF-18]	Secure Software, Inc.. "The CLASP Application Security Process". 2005. <https://cwe.mitre.org/documents/sources/TheCLASPApplicationSecurityProcess.pdf>. (URL validated: 2024-11-17)

Content History

Submissions
Submission Date	Submitter	Organization
2006-07-19 (CWE Draft 3, 2006-07-19)	CLASP
2006-07-19 (CWE Draft 3, 2006-07-19)
Contributions
Contribution Date	Contributor	Organization
2022-07-11	Nick Johnston
2022-07-11	Identified incorrect language tag in demonstrative example.
Modifications
Modification Date	Modifier	Organization
2023-06-29	CWE Content Team	MITRE
2023-06-29	updated Mapping_Notes
2023-04-27	CWE Content Team	MITRE
2023-04-27	updated Detection_Factors, References, Relationships
2023-01-31	CWE Content Team	MITRE
2023-01-31	updated Description
2022-10-13	CWE Content Team	MITRE
2022-10-13	updated Demonstrative_Examples
2021-10-28	CWE Content Team	MITRE
2021-10-28	updated Relationships
2021-07-20	CWE Content Team	MITRE
2021-07-20	updated Relationships
2020-12-10	CWE Content Team	MITRE
2020-12-10	updated Potential_Mitigations, Related_Attack_Patterns
2020-02-24	CWE Content Team	MITRE
2020-02-24	updated Applicable_Platforms, Description, Name, Observed_Examples, References, Relationships, Weakness_Ordinalities
2019-09-19	CWE Content Team	MITRE
2019-09-19	updated Demonstrative_Examples, Observed_Examples
2019-06-20	CWE Content Team	MITRE
2019-06-20	updated Relationships
2019-01-03	CWE Content Team	MITRE
2019-01-03	updated Taxonomy_Mappings
2018-03-27	CWE Content Team	MITRE
2018-03-27	updated References, Relationships
2017-11-08	CWE Content Team	MITRE
2017-11-08	updated Applicable_Platforms, Modes_of_Introduction, References, Relationships, Taxonomy_Mappings
2014-07-30	CWE Content Team	MITRE
2014-07-30	updated Relationships, Taxonomy_Mappings
2014-06-23	CWE Content Team	MITRE
2014-06-23	updated Relationships
2013-07-17	CWE Content Team	MITRE
2013-07-17	updated References
2012-05-11	CWE Content Team	MITRE
2012-05-11	updated References, Related_Attack_Patterns, Relationships
2011-09-13	CWE Content Team	MITRE
2011-09-13	updated Relationships, Taxonomy_Mappings
2011-06-27	CWE Content Team	MITRE
2011-06-27	updated Relationships
2011-06-01	CWE Content Team	MITRE
2011-06-01	updated Relationships, Taxonomy_Mappings
2011-03-29	CWE Content Team	MITRE
2011-03-29	updated Demonstrative_Examples, Observed_Examples, Relationships
2010-09-27	CWE Content Team	MITRE
2010-09-27	updated Potential_Mitigations, Relationships
2010-09-09		Veracode
2010-09-09	Suggested OWASP Top Ten mapping
2010-06-21	CWE Content Team	MITRE
2010-06-21	updated Common_Consequences, Detection_Factors, Potential_Mitigations, References
2010-04-05	CWE Content Team	MITRE
2010-04-05	updated Related_Attack_Patterns
2010-02-16	CWE Content Team	MITRE
2010-02-16	updated Detection_Factors, References, Relationships
2009-12-28	CWE Content Team	MITRE
2009-12-28	updated Demonstrative_Examples, Name, Potential_Mitigations, References, Time_of_Introduction
2009-03-10	CWE Content Team	MITRE
2009-03-10	updated Demonstrative_Examples, Potential_Mitigations, Relationships
2009-01-12	CWE Content Team	MITRE
2009-01-12	updated Demonstrative_Examples, Description, Name, Observed_Examples, Other_Notes, Potential_Mitigations, Relationships, Time_of_Introduction
2008-10-14	CWE Content Team	MITRE
2008-10-14	updated Relationships
2008-09-08	CWE Content Team	MITRE
2008-09-08	updated Applicable_Platforms, Common_Consequences, Relationships, Other_Notes, Taxonomy_Mappings
2008-08-15		Veracode
2008-08-15	Suggested OWASP Top Ten 2004 mapping
2008-07-01	Eric Dalci	Cigital
2008-07-01	updated Time_of_Introduction
Previous Entry Names
Change Date	Previous Entry Name
2009-01-12	Error Message Information Leaks
2009-12-28	Error Message Information Leak
2020-02-24	Information Exposure Through an Error Message

Weakness ID: 754

Vulnerability Mapping: ALLOWED This CWE ID could be used to map to real-world vulnerabilities in limited situations requiring careful review (with careful review of mapping notes)
Abstraction: Class Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.

View customized information:

Description

The product does not check or incorrectly checks for unusual or exceptional conditions that are not expected to occur frequently during day to day operation of the product.

Extended Description

The programmer may assume that certain events or conditions will never occur or do not need to be worried about, such as low memory conditions, lack of access to resources due to restrictive permissions, or misbehaving clients or components. However, attackers may intentionally trigger these unusual conditions, thus violating the programmer's assumptions, possibly introducing instability, incorrect behavior, or a vulnerability.

Note that this entry is not exclusively about the use of exceptions and exception handling, which are mechanisms for both checking and handling unusual or unexpected conditions.

Common Consequences

Impact	Details
DoS: Crash, Exit, or Restart; Unexpected State	Scope: Integrity, Availability The data which were produced as a result of a function call could be in a bad state upon return. If the return value is not checked, then this bad data may be used in operations, possibly leading to a crash or other unintended behaviors.

Potential Mitigations

Phase(s)	Mitigation
Requirements	Strategy: Language Selection Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. Choose languages with features such as exception handling that force the programmer to anticipate unusual conditions that may generate exceptions. Custom exceptions may need to be developed to handle unusual business-logic conditions. Be careful not to pass sensitive exceptions back to the user (CWE-209, CWE-248).
Implementation	Check the results of all functions that return a value and verify that the value is expected. Effectiveness: High Note: Checking the return value of the function will typically be sufficient, however beware of race conditions (CWE-362) in a concurrent environment.
Implementation	If using exception handling, catch and throw specific exceptions instead of overly-general exceptions (CWE-396, CWE-397). Catch and handle exceptions as locally as possible so that exceptions do not propagate too far up the call stack (CWE-705). Avoid unchecked or uncaught exceptions where feasible (CWE-248). Effectiveness: High Note: Using specific exceptions, and ensuring that exceptions are checked, helps programmers to anticipate and appropriately handle many unusual events that could occur.
Implementation	Ensure that error messages only contain minimal details that are useful to the intended audience and no one else. The messages need to strike the balance between being too cryptic (which can confuse users) or being too detailed (which may reveal more than intended). The messages should not reveal the methods that were used to determine the error. Attackers can use detailed information to refine or optimize their original attack, thereby increasing their chances of success. If errors must be captured in some detail, record them in log messages, but consider what could occur if the log messages can be viewed by attackers. Highly sensitive information such as passwords should never be saved to log files. Avoid inconsistent messaging that might accidentally tip off an attacker about internal state, such as whether a user account exists or not. Exposing additional information to a potential attacker in the context of an exceptional condition can help the attacker determine what attack vectors are most likely to succeed beyond DoS.
Implementation	Strategy: Input Validation Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does. When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue." Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright. Note: Performing extensive input validation does not help with handling unusual conditions, but it will minimize their occurrences and will make it more difficult for attackers to trigger them.
Architecture and Design; Implementation	If the program must fail, ensure that it fails gracefully (fails closed). There may be a temptation to simply let the program fail poorly in cases such as low memory conditions, but an attacker may be able to assert control before the software has fully exited. Alternately, an uncontrolled failure could cause cascading problems with other downstream components; for example, the program could send a signal to a downstream process so the process immediately knows that a problem has occurred and has a better chance of recovery.
Architecture and Design	Use system limits, which should help to prevent resource exhaustion. However, the product should still handle low resource conditions since they may still occur.

Relationships

Relevant to the view "Research Concepts" (View-1000)

Nature	Type	ID	Name
ChildOf	Pillar - a weakness that is the most abstract type of weakness and represents a theme for all class/base/variant weaknesses related to it. A Pillar is different from a Category as a Pillar is still technically a type of weakness that describes a mistake, while a Category represents a common characteristic used to group related things.	703	Improper Check or Handling of Exceptional Conditions
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	252	Unchecked Return Value
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	253	Incorrect Check of Function Return Value
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	273	Improper Check for Dropped Privileges
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	354	Improper Validation of Integrity Check Value
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	391	Unchecked Error Condition
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	394	Unexpected Status Code or Return Value
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	476	NULL Pointer Dereference
CanPrecede	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	416	Use After Free

Relevant to the view "Weaknesses for Simplified Mapping of Published Vulnerabilities" (View-1003)

Nature	Type	ID	Name
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1003	Weaknesses for Simplified Mapping of Published Vulnerabilities
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	252	Unchecked Return Value
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	273	Improper Check for Dropped Privileges
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	476	NULL Pointer Dereference

Relevant to the view "Architectural Concepts" (View-1008)

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1012	Cross Cutting

Background Details

Many functions will return some value about the success of their actions. This will alert the program whether or not to handle any errors caused by that function.

Modes Of Introduction

Phase	Note
Implementation	REALIZATION: This weakness is caused during implementation of an architectural security tactic.

Applicable Platforms

Languages

Class: Not Language-Specific (Undetermined Prevalence)

Likelihood Of Exploit

Medium

Demonstrative Examples

Example 1

Consider the following code segment:

(bad code)

Example Language: C

char buf[10], cp_buf[10];
fgets(buf, 10, stdin);
strcpy(cp_buf, buf);

The programmer expects that when fgets() returns, buf will contain a null-terminated string of length 9 or less. But if an I/O error occurs, fgets() will not null-terminate buf. Furthermore, if the end of the file is reached before any characters are read, fgets() returns without writing anything to buf. In both of these situations, fgets() signals that something unusual has happened by returning NULL, but in this code, the warning will not be noticed. The lack of a null terminator in buf can result in a buffer overflow in the subsequent call to strcpy().

Example 2

The following code does not check to see if memory allocation succeeded before attempting to use the pointer returned by malloc().

(bad code)

Example Language: C

buf = (char*) malloc(req_size);
strncpy(buf, xfer, req_size);

The traditional defense of this coding error is: "If my program runs out of memory, it will fail. It doesn't matter whether I handle the error or simply allow the program to die with a segmentation fault when it tries to dereference the null pointer." This argument ignores three important considerations:

Depending upon the type and size of the application, it may be possible to free memory that is being used elsewhere so that execution can continue.
It is impossible for the program to perform a graceful exit if required. If the program is performing an atomic operation, it can leave the system in an inconsistent state.
The programmer has lost the opportunity to record diagnostic information. Did the call to malloc() fail because req_size was too large or because there were too many requests being handled at the same time? Or was it caused by a memory leak that has built up over time? Without handling the error, there is no way to know.

Example 3

The following examples read a file into a byte array.

(bad code)

Example Language: C#

char[] byteArray = new char[1024];
for (IEnumerator i=users.GetEnumerator(); i.MoveNext() ;i.Current()) {

String userName = (String) i.Current();
String pFileName = PFILE_ROOT + "/" + userName;
StreamReader sr = new StreamReader(pFileName);
sr.Read(byteArray,0,1024);//the file is always 1k bytes
sr.Close();
processPFile(userName, byteArray);

}

(bad code)

Example Language: Java

FileInputStream fis;
byte[] byteArray = new byte[1024];
for (Iterator i=users.iterator(); i.hasNext();) {

String userName = (String) i.next();
String pFileName = PFILE_ROOT + "/" + userName;
FileInputStream fis = new FileInputStream(pFileName);
fis.read(byteArray); // the file is always 1k bytes
fis.close();
processPFile(userName, byteArray);

The code loops through a set of users, reading a private data file for each user. The programmer assumes that the files are always 1 kilobyte in size and therefore ignores the return value from Read(). If an attacker can create a smaller file, the program will recycle the remainder of the data from the previous user and treat it as though it belongs to the attacker.

Example 4

The following code does not check to see if the string returned by getParameter() is null before calling the member function compareTo(), potentially causing a NULL dereference.

(bad code)

Example Language: Java

String itemName = request.getParameter(ITEM_NAME);
if (itemName.compareTo(IMPORTANT_ITEM) == 0) {

...

}
...

The following code does not check to see if the string returned by the Item property is null before calling the member function Equals(), potentially causing a NULL dereference.

(bad code)

Example Language: Java

String itemName = request.Item(ITEM_NAME);
if (itemName.Equals(IMPORTANT_ITEM)) {

...

}
...

The traditional defense of this coding error is: "I know the requested value will always exist because.... If it does not exist, the program cannot perform the desired behavior so it doesn't matter whether I handle the error or simply allow the program to die dereferencing a null value." But attackers are skilled at finding unexpected paths through programs, particularly when exceptions are involved.

Example 5

The following code shows a system property that is set to null and later dereferenced by a programmer who mistakenly assumes it will always be defined.

(bad code)

Example Language: Java

System.clearProperty("os.name");
...
String os = System.getProperty("os.name");
if (os.equalsIgnoreCase("Windows 95")) System.out.println("Not supported");

Example 6

The following VB.NET code does not check to make sure that it has read 50 bytes from myfile.txt. This can cause DoDangerousOperation() to operate on an unexpected value.

(bad code)

Example Language: C#

Dim MyFile As New FileStream("myfile.txt", FileMode.Open, FileAccess.Read, FileShare.Read)
Dim MyArray(50) As Byte
MyFile.Read(MyArray, 0, 50)
DoDangerousOperation(MyArray(20))

In .NET, it is not uncommon for programmers to misunderstand Read() and related methods that are part of many System.IO classes. The stream and reader classes do not consider it to be unusual or exceptional if only a small amount of data becomes available. These classes simply add the small amount of data to the return buffer, and set the return value to the number of bytes or characters read. There is no guarantee that the amount of data returned is equal to the amount of data requested.

Example 7

This example takes an IP address from a user, verifies that it is well formed and then looks up the hostname and copies it into a buffer.

(bad code)

Example Language: C

void host_lookup(char *user_supplied_addr){

}

If an attacker provides an address that appears to be well-formed, but the address does not resolve to a hostname, then the call to gethostbyaddr() will return NULL. Since the code does not check the return value from gethostbyaddr (CWE-252), a NULL pointer dereference (CWE-476) would then occur in the call to strcpy().

Note that this code is also vulnerable to a buffer overflow (CWE-119).

Example 8

In the following C/C++ example the method outputStringToFile opens a file in the local filesystem and outputs a string to the file. The input parameters output and filename contain the string to output to the file and the name of the file respectively.

(bad code)

Example Language: C++

int outputStringToFile(char *output, char *filename) {

openFileToWrite(filename);
writeToFile(output);
closeFile(filename);

}

However, this code does not check the return values of the methods openFileToWrite, writeToFile, closeFile to verify that the file was properly opened and closed and that the string was successfully written to the file. The return values for these methods should be checked to determine if the method was successful and allow for detection of errors or unexpected conditions as in the following example.

(good code)

Example Language: C++

int outputStringToFile(char *output, char *filename) {

int isOutput = SUCCESS;

int isOpen = openFileToWrite(filename);
if (isOpen == FAIL) {

printf("Unable to open file %s", filename);
isOutput = FAIL;

}
else {

int isWrite = writeToFile(output);
if (isWrite == FAIL) {

printf("Unable to write to file %s", filename);
isOutput = FAIL;

}

int isClose = closeFile(filename);
if (isClose == FAIL)

isOutput = FAIL;

}
return isOutput;

}

Example 9

In the following Java example the method readFromFile uses a FileReader object to read the contents of a file. The FileReader object is created using the File object readFile, the readFile object is initialized using the setInputFile method. The setInputFile method should be called before calling the readFromFile method.

(bad code)

Example Language: Java

private File readFile = null;

public void setInputFile(String inputFile) {

// create readFile File object from string containing name of file

}

public void readFromFile() {

try {

reader = new FileReader(readFile);

// read input file

} catch (FileNotFoundException ex) {...}

}

However, the readFromFile method does not check to see if the readFile object is null, i.e. has not been initialized, before creating the FileReader object and reading from the input file. The readFromFile method should verify whether the readFile object is null and output an error message and raise an exception if the readFile object is null, as in the following code.

(good code)

Example Language: Java

private File readFile = null;

public void setInputFile(String inputFile) {

// create readFile File object from string containing name of file

}

public void readFromFile() {

try {

if (readFile == null) {

System.err.println("Input file has not been set, call setInputFile method before calling openInputFile");
throw NullPointerException;

}

reader = new FileReader(readFile);

// read input file

} catch (FileNotFoundException ex) {...}
catch (NullPointerException ex) {...}

}

Selected Observed Examples

Reference	Description
CVE-2023-49286	Chain: function in web caching proxy does not correctly check a return value (CWE-253) leading to a reachable assertion (CWE-617)
CVE-2007-3798	Unchecked return value leads to resultant integer overflow and code execution.
CVE-2006-4447	Program does not check return value when invoking functions to drop privileges, which could leave users with higher privileges than expected by forcing those functions to fail.
CVE-2006-2916	Program does not check return value when invoking functions to drop privileges, which could leave users with higher privileges than expected by forcing those functions to fail.

Detection Methods

Method

Details

Automated Static Analysis

Automated static analysis may be useful for detecting unusual conditions involving system resources or common programming idioms, but not for violations of business rules.

Effectiveness: Moderate

Manual Dynamic Analysis

Identify error conditions that are not likely to occur during normal usage and trigger them. For example, run the program under low memory conditions, run with insufficient privileges or permissions, interrupt a transaction before it is completed, or disable connectivity to basic network services such as DNS. Monitor the software for any unexpected behavior. If you trigger an unhandled exception or similar error that was discovered and handled by the application's environment, it may still indicate unexpected conditions that were not handled by the application itself.

Memberships

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	742	CERT C Secure Coding Standard (2008) Chapter 9 - Memory Management (MEM)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	802	2010 Top 25 - Risky Resource Management
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	867	2011 Top 25 - Weaknesses On the Cusp
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	876	CERT C++ Secure Coding Section 08 - Memory Management (MEM)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	880	CERT C++ Secure Coding Section 12 - Exceptions and Error Handling (ERR)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	962	SFP Secondary Cluster: Unchecked Status Condition
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1141	SEI CERT Oracle Secure Coding Standard for Java - Guidelines 07. Exceptional Behavior (ERR)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1181	SEI CERT Perl Coding Standard - Guidelines 03. Expressions (EXP)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1364	ICS Communications: Zone Boundary Failures
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1405	Comprehensive Categorization: Improper Check or Handling of Exceptional Conditions

Vulnerability Mapping Notes

Usage	ALLOWED-WITH-REVIEW (this CWE ID could be used to map to real-world vulnerabilities in limited situations requiring careful review)
Reason	Abstraction
Rationale	This CWE entry is a Class and might have Base-level children that would be more appropriate
Comments	Examine children of this entry to see if there is a better fit

Notes

Relationship

Sometimes, when a return value can be used to indicate an error, an unchecked return value is a code-layer instance of a missing application-layer check for exceptional conditions. However, return values are not always needed to communicate exceptional conditions. For example, expiration of resources, values passed by reference, asynchronously modified data, sockets, etc. may indicate exceptional conditions without the use of a return value.

Taxonomy Mappings

Mapped Taxonomy Name	Node ID	Fit	Mapped Node Name
SEI CERT Perl Coding Standard	EXP31-PL	CWE More Abstract	Do not suppress or ignore exceptions
ISA/IEC 62443	Part 4-2		Req CR 3.5
ISA/IEC 62443	Part 4-2		Req CR 3.7

References

[REF-62]	Mark Dowd, John McDonald and Justin Schuh. "The Art of Software Security Assessment". Chapter 7, "Program Building Blocks" Page 341. 1st Edition. Addison Wesley. 2006.
[REF-62]	Mark Dowd, John McDonald and Justin Schuh. "The Art of Software Security Assessment". Chapter 1, "Exceptional Conditions," Page 22. 1st Edition. Addison Wesley. 2006.
[REF-44]	Michael Howard, David LeBlanc and John Viega. "24 Deadly Sins of Software Security". "Sin 11: Failure to Handle Errors Correctly." Page 183. McGraw-Hill. 2010.
[REF-622]	Frank Kim. "Top 25 Series - Rank 15 - Improper Check for Unusual or Exceptional Conditions". SANS Software Security Institute. 2010-03-15. <https://www.sans.org/blog/top-25-series-rank-15-improper-check-for-unusual-or-exceptional-conditions/>. (URL validated: 2023-04-07)

Content History

Submissions
Submission Date	Submitter	Organization
2009-03-03 (CWE 1.3, 2009-03-10)	CWE Content Team	MITRE
2009-03-03 (CWE 1.3, 2009-03-10)	New entry for reorganization of CWE-703.
Contributions
Contribution Date	Contributor	Organization
2023-04-25	"Mapping CWE to 62443" Sub-Working Group	CWE-CAPEC ICS/OT SIG
2023-04-25	Suggested mappings to ISA/IEC 62443.
Modifications
Modification Date	Modifier	Organization
2024-07-16 (CWE 4.15, 2024-07-16)	CWE Content Team	MITRE
2024-07-16 (CWE 4.15, 2024-07-16)	updated Relationships
2024-02-29 (CWE 4.14, 2024-02-29)	CWE Content Team	MITRE
2024-02-29 (CWE 4.14, 2024-02-29)	updated Observed_Examples
2023-06-29	CWE Content Team	MITRE
2023-06-29	updated Mapping_Notes
2023-04-27	CWE Content Team	MITRE
2023-04-27	updated References, Relationships, Taxonomy_Mappings
2023-01-31	CWE Content Team	MITRE
2023-01-31	updated Description, Potential_Mitigations
2022-04-28	CWE Content Team	MITRE
2022-04-28	updated Relationships
2021-07-20	CWE Content Team	MITRE
2021-07-20	updated Relationships
2021-03-15	CWE Content Team	MITRE
2021-03-15	updated Demonstrative_Examples, Relationships
2020-12-10	CWE Content Team	MITRE
2020-12-10	updated Potential_Mitigations
2020-06-25	CWE Content Team	MITRE
2020-06-25	updated Potential_Mitigations
2020-02-24	CWE Content Team	MITRE
2020-02-24	updated Potential_Mitigations, Relationships
2019-06-20	CWE Content Team	MITRE
2019-06-20	updated Description, Relationships
2019-01-03	CWE Content Team	MITRE
2019-01-03	updated Relationships, Taxonomy_Mappings
2017-11-08	CWE Content Team	MITRE
2017-11-08	updated Modes_of_Introduction, References, Relationships, Taxonomy_Mappings
2017-01-19	CWE Content Team	MITRE
2017-01-19	updated Relationships
2015-12-07	CWE Content Team	MITRE
2015-12-07	updated Relationships
2014-07-30	CWE Content Team	MITRE
2014-07-30	updated Demonstrative_Examples, Relationships
2013-02-21	CWE Content Team	MITRE
2013-02-21	updated Relationships
2012-10-30	CWE Content Team	MITRE
2012-10-30	updated Potential_Mitigations
2012-05-11	CWE Content Team	MITRE
2012-05-11	updated Relationships
2011-09-13	CWE Content Team	MITRE
2011-09-13	updated Relationships, Taxonomy_Mappings
2011-06-27	CWE Content Team	MITRE
2011-06-27	updated Common_Consequences, Related_Attack_Patterns, Relationships
2011-06-01	CWE Content Team	MITRE
2011-06-01	updated Common_Consequences
2011-03-29	CWE Content Team	MITRE
2011-03-29	updated Description, Relationships
2010-12-13	CWE Content Team	MITRE
2010-12-13	updated Relationship_Notes
2010-09-27	CWE Content Team	MITRE
2010-09-27	updated Potential_Mitigations
2010-06-21	CWE Content Team	MITRE
2010-06-21	updated Common_Consequences, Detection_Factors, Potential_Mitigations, References
2010-04-05	CWE Content Team	MITRE
2010-04-05	updated Demonstrative_Examples, Related_Attack_Patterns
2010-02-16	CWE Content Team	MITRE
2010-02-16	updated Background_Details, Common_Consequences, Demonstrative_Examples, Description, Detection_Factors, Name, Observed_Examples, Potential_Mitigations, References, Related_Attack_Patterns, Relationship_Notes, Relationships
2009-12-28	CWE Content Team	MITRE
2009-12-28	updated Applicable_Platforms, Likelihood_of_Exploit, Time_of_Introduction
2009-07-27	CWE Content Team	MITRE
2009-07-27	updated Relationships
Previous Entry Names
Change Date	Previous Entry Name
2010-02-16	Improper Check for Exceptional Conditions

Weakness ID: 116

Vulnerability Mapping: ALLOWED This CWE ID could be used to map to real-world vulnerabilities in limited situations requiring careful review (with careful review of mapping notes)
Abstraction: Class Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.

View customized information:

Description

Extended Description

Improper encoding or escaping can allow attackers to change the commands that are sent to another component, inserting malicious commands instead.

Most products follow a certain protocol that uses structured messages for communication between components, such as queries or commands. These structured messages can contain raw data interspersed with metadata or control information. For example, "GET /index.html HTTP/1.1" is a structured message containing a command ("GET") with a single argument ("/index.html") and metadata about which protocol version is being used ("HTTP/1.1").

If an application uses attacker-supplied inputs to construct a structured message without properly encoding or escaping, then the attacker could insert special characters that will cause the data to be interpreted as control information or metadata. Consequently, the component that receives the output will perform the wrong operations, or otherwise interpret the data incorrectly.

Alternate Terms

Output Sanitization
Output Validation
Output Encoding

Common Consequences

Impact	Details
Modify Application Data	Scope: Integrity The communications between components can be modified in unexpected ways. Unexpected commands can be executed, bypassing other security mechanisms. Incoming data can be misinterpreted.
Execute Unauthorized Code or Commands	Scope: Integrity, Confidentiality, Availability, Access Control The communications between components can be modified in unexpected ways. Unexpected commands can be executed, bypassing other security mechanisms. Incoming data can be misinterpreted.
Bypass Protection Mechanism	Scope: Confidentiality The communications between components can be modified in unexpected ways. Unexpected commands can be executed, bypassing other security mechanisms. Incoming data can be misinterpreted.

Potential Mitigations

Phase(s)	Mitigation
Architecture and Design	Strategy: Libraries or Frameworks Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, consider using the ESAPI Encoding control [REF-45] or a similar tool, library, or framework. These will help the programmer encode outputs in a manner less prone to error. Alternately, use built-in functions, but consider using wrappers in case those functions are discovered to have a vulnerability.
Architecture and Design	Strategy: Parameterization If available, use structured mechanisms that automatically enforce the separation between data and code. These mechanisms may be able to provide the relevant quoting, encoding, and validation automatically, instead of relying on the developer to provide this capability at every point where output is generated. For example, stored procedures can enforce database query structure and reduce the likelihood of SQL injection.
Architecture and Design; Implementation	Understand the context in which your data will be used and the encoding that will be expected. This is especially important when transmitting data between different components, or when generating outputs that can contain multiple encodings at the same time, such as web pages or multi-part mail messages. Study all expected communication protocols and data representations to determine the required encoding strategies.
Architecture and Design	In some cases, input validation may be an important strategy when output encoding is not a complete solution. For example, you may be providing the same output that will be processed by multiple consumers that use different encodings or representations. In other cases, you may be required to allow user-supplied input to contain control information, such as limited HTML tags that support formatting in a wiki or bulletin board. When this type of requirement must be met, use an extremely strict allowlist to limit which control sequences can be used. Verify that the resulting syntactic structure is what you expect. Use your normal encoding methods for the remainder of the input.
Architecture and Design	Use input validation as a defense-in-depth measure to reduce the likelihood of output encoding errors (see CWE-20).
Requirements	Fully specify which encodings are required by components that will be communicating with each other.
Implementation	When exchanging data between components, ensure that both components are using the same character encoding. Ensure that the proper encoding is applied at each interface. Explicitly set the encoding you are using whenever the protocol allows you to do so.

Relationships

Relevant to the view "Research Concepts" (View-1000)

Nature	Type	ID	Name
ChildOf	Pillar - a weakness that is the most abstract type of weakness and represents a theme for all class/base/variant weaknesses related to it. A Pillar is different from a Category as a Pillar is still technically a type of weakness that describes a mistake, while a Category represents a common characteristic used to group related things.	707	Improper Neutralization
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	117	Improper Output Neutralization for Logs
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	644	Improper Neutralization of HTTP Headers for Scripting Syntax
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	838	Inappropriate Encoding for Output Context
CanPrecede	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	74	Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')

Relevant to the view "Weaknesses for Simplified Mapping of Published Vulnerabilities" (View-1003)

Nature	Type	ID	Name
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1003	Weaknesses for Simplified Mapping of Published Vulnerabilities
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	838	Inappropriate Encoding for Output Context

Modes Of Introduction

Phase	Note
Implementation
Operation

Applicable Platforms

Languages	Class: Not Language-Specific (Often Prevalent)
Technologies	AI/ML (Undetermined Prevalence) Database Server (Often Prevalent) Web Server (Often Prevalent)

Likelihood Of Exploit

High

Demonstrative Examples

Example 1

This code displays an email address that was submitted as part of a form.

(bad code)

Example Language: JSP

<% String email = request.getParameter("email"); %>
...
Email Address: <%= email %>

The value read from the form parameter is reflected back to the client browser without having been encoded prior to output, allowing various XSS attacks (CWE-79).

Example 2

Consider a chat application in which a front-end web application communicates with a back-end server. The back-end is legacy code that does not perform authentication or authorization, so the front-end must implement it. The chat protocol supports two commands, SAY and BAN, although only administrators can use the BAN command. Each argument must be separated by a single space. The raw inputs are URL-encoded. The messaging protocol allows multiple commands to be specified on the same line if they are separated by a "|" character.

First let's look at the back end command processor code

(bad code)

Example Language: Perl

$inputString = readLineFromFileHandle($serverFH);

# generate an array of strings separated by the "|" character.
@commands = split(/\|/, $inputString);

foreach $cmd (@commands) {

# separate the operator from its arguments based on a single whitespace
($operator, $args) = split(/ /, $cmd, 2);

$args = UrlDecode($args);
if ($operator eq "BAN") {

ExecuteBan($args);

}
elsif ($operator eq "SAY") {

ExecuteSay($args);

}

The front end web application receives a command, encodes it for sending to the server, performs the authorization check, and sends the command to the server.

(bad code)

Example Language: Perl

$inputString = GetUntrustedArgument("command");
($cmd, $argstr) = split(/\s+/, $inputString, 2);

# removes extra whitespace and also changes CRLF's to spaces
$argstr =~ s/\s+/ /gs;

$argstr = UrlEncode($argstr);
if (($cmd eq "BAN") && (! IsAdministrator($username))) {

die "Error: you are not the admin.\n";

}

# communicate with file server using a file handle
$fh = GetServerFileHandle("myserver");

print $fh "$cmd $argstr\n";

It is clear that, while the protocol and back-end allow multiple commands to be sent in a single request, the front end only intends to send a single command. However, the UrlEncode function could leave the "|" character intact. If an attacker provides:

(attack code)

SAY hello world|BAN user12

then the front end will see this is a "SAY" command, and the $argstr will look like "hello world | BAN user12". Since the command is "SAY", the check for the "BAN" command will fail, and the front end will send the URL-encoded command to the back end:

(result)

SAY hello%20world|BAN%20user12

The back end, however, will treat these as two separate commands:

(result)

SAY hello world
BAN user12

Notice, however, that if the front end properly encodes the "|" with "%7C", then the back end will only process a single command.

Example 3

This example takes user input, passes it through an encoding scheme and then creates a directory specified by the user.

(bad code)

Example Language: Perl

sub GetUntrustedInput {

return($ARGV[0]);

}

sub encode {

my($str) = @_;
$str =~ s/\&/\&/gs;
$str =~ s/\"/\"/gs;
$str =~ s/\'/\'/gs;
$str =~ s/\</\</gs;
$str =~ s/\>/\>/gs;
return($str);

}

sub doit {

my $uname = encode(GetUntrustedInput("username"));
print "<b>Welcome, $uname!</b><p>\n";
system("cd /home/$uname; /bin/ls -l");

}

The programmer attempts to encode dangerous characters, however the denylist for encoding is incomplete (CWE-184) and an attacker can still pass a semicolon, resulting in a chain with command injection (CWE-77).

Additionally, the encoding routine is used inappropriately with command execution. An attacker doesn't even need to insert their own semicolon. The attacker can instead leverage the encoding routine to provide the semicolon to separate the commands. If an attacker supplies a string of the form:

(attack code)

' pwd

then the program will encode the apostrophe and insert the semicolon, which functions as a command separator when passed to the system function. This allows the attacker to complete the command injection.

Selected Observed Examples

Reference	Description
CVE-2021-41232	Chain: authentication routine in Go-based agile development product does not escape user name (CWE-116), allowing LDAP injection (CWE-90)
CVE-2008-4636	OS command injection in backup software using shell metacharacters in a filename; correct behavior would require that this filename could not be changed.
CVE-2008-0769	Web application does not set the charset when sending a page to a browser, allowing for XSS exploitation when a browser chooses an unexpected encoding.
CVE-2008-0005	Program does not set the charset when sending a page to a browser, allowing for XSS exploitation when a browser chooses an unexpected encoding.
CVE-2008-5573	SQL injection via password parameter; a strong password might contain "&"
CVE-2008-3773	Cross-site scripting in chat application via a message subject, which normally might contain "&" and other XSS-related characters.
CVE-2008-0757	Cross-site scripting in chat application via a message, which normally might be allowed to contain arbitrary content.

Detection Methods

Method	Details
Automated Static Analysis	This weakness can often be detected using automated static analysis tools. Many modern tools use data flow analysis or constraint-based techniques to minimize the number of false positives. Effectiveness: Moderate Note:This is not a perfect solution, since 100% accuracy and coverage are not feasible.
Automated Dynamic Analysis	This weakness can be detected using dynamic tools and techniques that interact with the software using large test suites with many diverse inputs, such as fuzz testing (fuzzing), robustness testing, and fault injection. The software's operation may slow down, but it should not become unstable, crash, or generate incorrect results.

Memberships

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	751	2009 Top 25 - Insecure Interaction Between Components
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	845	The CERT Oracle Secure Coding Standard for Java (2011) Chapter 2 - Input Validation and Data Sanitization (IDS)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	883	CERT C++ Secure Coding Section 49 - Miscellaneous (MSC)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	992	SFP Secondary Cluster: Faulty Input Transformation
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1134	SEI CERT Oracle Secure Coding Standard for Java - Guidelines 00. Input Validation and Data Sanitization (IDS)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1179	SEI CERT Perl Coding Standard - Guidelines 01. Input Validation and Data Sanitization (IDS)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1347	OWASP Top Ten 2021 Category A03:2021 - Injection
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1407	Comprehensive Categorization: Improper Neutralization

Vulnerability Mapping Notes

Usage	ALLOWED-WITH-REVIEW (this CWE ID could be used to map to real-world vulnerabilities in limited situations requiring careful review)
Reason	Abstraction
Rationale	This CWE entry is a Class and might have Base-level children that would be more appropriate
Comments	Examine children of this entry to see if there is a better fit

Notes

Relationship

This weakness is primary to all weaknesses related to injection (CWE-74) since the inherent nature of injection involves the violation of structured messages.

Relationship

CWE-116 and CWE-20 have a close association because, depending on the nature of the structured message, proper input validation can indirectly prevent special characters from changing the meaning of a structured message. For example, by validating that a numeric ID field should only contain the 0-9 characters, the programmer effectively prevents injection attacks.

However, input validation is not always sufficient, especially when less stringent data types must be supported, such as free-form text. Consider a SQL injection scenario in which a last name is inserted into a query. The name "O'Reilly" would likely pass the validation step since it is a common last name in the English language. However, it cannot be directly inserted into the database because it contains the "'" apostrophe character, which would need to be escaped or otherwise neutralized. In this case, stripping the apostrophe might reduce the risk of SQL injection, but it would produce incorrect behavior because the wrong name would be recorded.

Terminology

The usage of the "encoding" and "escaping" terms varies widely. For example, in some programming languages, the terms are used interchangeably, while other languages provide APIs that use both terms for different tasks. This overlapping usage extends to the Web, such as the "escape" JavaScript function whose purpose is stated to be encoding. The concepts of encoding and escaping predate the Web by decades. Given such a context, it is difficult for CWE to adopt a consistent vocabulary that will not be misinterpreted by some constituency.

Theoretical

This is a data/directive boundary error in which data boundaries are not sufficiently enforced before it is sent to a different control sphere.

Research Gap

While many published vulnerabilities are related to insufficient output encoding, there is such an emphasis on input validation as a protection mechanism that the underlying causes are rarely described. Within CVE, the focus is primarily on well-understood issues like cross-site scripting and SQL injection. It is likely that this weakness frequently occurs in custom protocols that support multiple encodings, which are not necessarily detectable with automated techniques.

Taxonomy Mappings

Mapped Taxonomy Name	Node ID	Fit	Mapped Node Name
WASC	22		Improper Output Handling
The CERT Oracle Secure Coding Standard for Java (2011)	IDS00-J	Exact	Sanitize untrusted data passed across a trust boundary
The CERT Oracle Secure Coding Standard for Java (2011)	IDS05-J		Use a subset of ASCII for file and path names
SEI CERT Oracle Coding Standard for Java	IDS00-J	Imprecise	Prevent SQL injection
SEI CERT Perl Coding Standard	IDS33-PL	Exact	Sanitize untrusted data passed across a trust boundary

Related Attack Patterns

CAPEC-ID	Attack Pattern Name
CAPEC-104	Cross Zone Scripting
CAPEC-73	User-Controlled Filename
CAPEC-81	Web Server Logs Tampering
CAPEC-85	AJAX Footprinting

References

[REF-45]	OWASP. "OWASP Enterprise Security API (ESAPI) Project". <http://www.owasp.org/index.php/ESAPI>.
[REF-46]	Joshbw. "Output Sanitization". 2008-09-18. <https://web.archive.org/web/20081208054333/http://analyticalengine.net/archives/58>. (URL validated: 2023-04-07)
[REF-47]	Niyaz PK. "Sanitizing user data: How and where to do it". 2008-09-11. <https://web.archive.org/web/20090105222005/http://www.diovo.com/2008/09/sanitizing-user-data-how-and-where-to-do-it/>. (URL validated: 2023-04-07)
[REF-48]	Jeremiah Grossman. "Input validation or output filtering, which is better?". 2007-01-30. <https://blog.jeremiahgrossman.com/2007/01/input-validation-or-output-filtering.html>. (URL validated: 2023-04-07)
[REF-49]	Jim Manico. "Input Validation - Not That Important". 2008-08-10. <https://manicode.blogspot.com/2008/08/input-validation-not-that-important.html>. (URL validated: 2023-04-07)
[REF-50]	Michael Eddington. "Preventing XSS with Correct Output Encoding". <http://phed.org/2008/05/19/preventing-xss-with-correct-output-encoding/>.
[REF-7]	Michael Howard and David LeBlanc. "Writing Secure Code". Chapter 11, "Canonical Representation Issues" Page 363. 2nd Edition. Microsoft Press. 2002-12-04. <https://www.microsoftpressstore.com/store/writing-secure-code-9780735617223>.

Content History

Submissions
Submission Date	Submitter	Organization
2006-07-19 (CWE Draft 3, 2006-07-19)	CWE Community
2006-07-19 (CWE Draft 3, 2006-07-19)	Submitted by members of the CWE community to extend early CWE versions
Modifications
Modification Date	Modifier	Organization
2024-07-16 (CWE 4.15, 2024-07-16)	CWE Content Team	MITRE
2024-07-16 (CWE 4.15, 2024-07-16)	updated Applicable_Platforms
2023-06-29	CWE Content Team	MITRE
2023-06-29	updated Mapping_Notes
2023-04-27	CWE Content Team	MITRE
2023-04-27	updated References, Relationships, Time_of_Introduction
2023-01-31	CWE Content Team	MITRE
2023-01-31	updated Description
2022-10-13	CWE Content Team	MITRE
2022-10-13	updated Observed_Examples
2021-10-28	CWE Content Team	MITRE
2021-10-28	updated Relationships
2021-03-15	CWE Content Team	MITRE
2021-03-15	updated Relationships, Terminology_Notes
2020-06-25	CWE Content Team	MITRE
2020-06-25	updated Applicable_Platforms, Demonstrative_Examples, Potential_Mitigations
2020-02-24	CWE Content Team	MITRE
2020-02-24	updated Relationships
2019-06-20	CWE Content Team	MITRE
2019-06-20	updated Relationships
2019-01-03	CWE Content Team	MITRE
2019-01-03	updated Relationships, Taxonomy_Mappings
2018-03-27	CWE Content Team	MITRE
2018-03-27	updated References
2017-11-08	CWE Content Team	MITRE
2017-11-08	updated Applicable_Platforms, Common_Consequences, Demonstrative_Examples, Likelihood_of_Exploit, References, Taxonomy_Mappings
2017-05-03	CWE Content Team	MITRE
2017-05-03	updated Related_Attack_Patterns
2017-01-19	CWE Content Team	MITRE
2017-01-19	updated Relationships
2015-12-07	CWE Content Team	MITRE
2015-12-07	updated Relationships
2014-07-30	CWE Content Team	MITRE
2014-07-30	updated Demonstrative_Examples, Relationships
2014-06-23	CWE Content Team	MITRE
2014-06-23	updated References
2012-10-30	CWE Content Team	MITRE
2012-10-30	updated Potential_Mitigations
2012-05-11	CWE Content Team	MITRE
2012-05-11	updated References, Relationships, Taxonomy_Mappings
2011-09-13	CWE Content Team	MITRE
2011-09-13	updated Relationships, Taxonomy_Mappings
2011-06-01	CWE Content Team	MITRE
2011-06-01	updated Common_Consequences, Relationships, Taxonomy_Mappings
2011-03-29	CWE Content Team	MITRE
2011-03-29	updated Relationship_Notes, Relationships
2010-06-21	CWE Content Team	MITRE
2010-06-21	updated Potential_Mitigations
2010-04-05	CWE Content Team	MITRE
2010-04-05	updated Potential_Mitigations
2010-02-16	CWE Content Team	MITRE
2010-02-16	updated Detection_Factors, Potential_Mitigations, References, Taxonomy_Mappings
2009-12-28	CWE Content Team	MITRE
2009-12-28	updated Demonstrative_Examples, Potential_Mitigations
2009-10-29	CWE Content Team	MITRE
2009-10-29	updated Relationships
2009-07-27	CWE Content Team	MITRE
2009-07-27	updated Demonstrative_Examples
2009-05-27	CWE Content Team	MITRE
2009-05-27	updated Related_Attack_Patterns
2009-03-10	CWE Content Team	MITRE
2009-03-10	updated Description, Potential_Mitigations
2009-01-12	CWE Content Team	MITRE
2009-01-12	updated Alternate_Terms, Applicable_Platforms, Common_Consequences, Demonstrative_Examples, Description, Likelihood_of_Exploit, Name, Observed_Examples, Potential_Mitigations, References, Relationship_Notes, Relationships, Research_Gaps, Terminology_Notes, Theoretical_Notes
2008-09-08	CWE Content Team	MITRE
2008-09-08	updated Name, Relationships
2008-07-01	Eric Dalci	Cigital
2008-07-01	updated Time_of_Introduction
2008-07-01	Sean Eidemiller	Cigital
2008-07-01	added/updated demonstrative examples
Previous Entry Names
Change Date	Previous Entry Name
2008-04-11	Output Validation
2008-09-09	Incorrect Output Sanitization
2009-01-12	Insufficient Output Sanitization

Weakness ID: 665

Vulnerability Mapping: DISCOURAGED This CWE ID should not be used to map to real-world vulnerabilities
Abstraction: Class Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.

View customized information:

Description

The product does not initialize or incorrectly initializes a resource, which might leave the resource in an unexpected state when it is accessed or used.

Extended Description

This can have security implications when the associated resource is expected to have certain properties or values, such as a variable that determines whether a user has been authenticated or not.

Common Consequences

Impact	Details
Read Memory; Read Application Data	Scope: Confidentiality When reusing a resource such as memory or a program variable, the original contents of that resource may not be cleared before it is sent to an untrusted party.
Bypass Protection Mechanism	Scope: Access Control If security-critical decisions rely on a variable having a "0" or equivalent value, and the programming language performs this initialization on behalf of the programmer, then a bypass of security may occur.
DoS: Crash, Exit, or Restart	Scope: Availability The uninitialized data may contain values that cause program flow to change in ways that the programmer did not intend. For example, if an uninitialized variable is used as an array index in C, then its previous contents may produce an index that is outside the range of the array, possibly causing a crash or an exit in other environments.

Potential Mitigations

Phase(s)	Mitigation
Requirements	Strategy: Language Selection Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, in Java, if the programmer does not explicitly initialize a variable, then the code could produce a compile-time error (if the variable is local) or automatically initialize the variable to the default value for the variable's type. In Perl, if explicit initialization is not performed, then a default value of undef is assigned, which is interpreted as 0, false, or an equivalent value depending on the context in which the variable is accessed.
Architecture and Design	Identify all variables and data stores that receive information from external sources, and apply input validation to make sure that they are only initialized to expected values.
Implementation	Explicitly initialize all your variables and other data stores, either during declaration or just before the first usage.
Implementation	Pay close attention to complex conditionals that affect initialization, since some conditions might not perform the initialization.
Implementation	Avoid race conditions (CWE-362) during initialization routines.
Build and Compilation	Run or compile your product with settings that generate warnings about uninitialized variables or data.
Testing	Use automated static analysis tools that target this type of weakness. Many modern techniques use data flow analysis to minimize the number of false positives. This is not a perfect solution, since 100% accuracy and coverage are not feasible.

Relationships

Relevant to the view "Research Concepts" (View-1000)

Nature	Type	ID	Name
ChildOf	Pillar - a weakness that is the most abstract type of weakness and represents a theme for all class/base/variant weaknesses related to it. A Pillar is different from a Category as a Pillar is still technically a type of weakness that describes a mistake, while a Category represents a common characteristic used to group related things.	664	Improper Control of a Resource Through its Lifetime
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	455	Non-exit on Failed Initialization
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	770	Allocation of Resources Without Limits or Throttling
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	908	Use of Uninitialized Resource
ParentOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	909	Missing Initialization of Resource
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	1279	Cryptographic Operations are run Before Supporting Units are Ready
ParentOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	1419	Incorrect Initialization of Resource

Relevant to the view "Weaknesses for Simplified Mapping of Published Vulnerabilities" (View-1003)

Nature	Type	ID	Name
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1003	Weaknesses for Simplified Mapping of Published Vulnerabilities
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	908	Use of Uninitialized Resource
ParentOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	909	Missing Initialization of Resource
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	1188	Initialization of a Resource with an Insecure Default

Relevant to the view "CISQ Quality Measures (2020)" (View-1305)

Nature	Type	ID	Name
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	456	Missing Initialization of a Variable
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	457	Use of Uninitialized Variable

Relevant to the view "CISQ Data Protection Measures" (View-1340)

Nature	Type	ID	Name
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	456	Missing Initialization of a Variable
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	457	Use of Uninitialized Variable

Modes Of Introduction

Phase	Note
Implementation	This weakness can occur in code paths that are not well-tested, such as rare error conditions. This is because the use of uninitialized data would be noticed as a bug during frequently-used functionality.
Operation

Applicable Platforms

Languages

Class: Not Language-Specific (Undetermined Prevalence)

Likelihood Of Exploit

Medium

Demonstrative Examples

Example 1

Here, a boolean initiailized field is consulted to ensure that initialization tasks are only completed once. However, the field is mistakenly set to true during static initialization, so the initialization code is never reached.

(bad code)

Example Language: Java

private boolean initialized = true;
public void someMethod() {

if (!initialized) {

// perform initialization tasks
...

initialized = true;

}

Example 2

The following code intends to limit certain operations to the administrator only.

(bad code)

Example Language: Perl

$username = GetCurrentUser();
$state = GetStateData($username);
if (defined($state)) {

$uid = ExtractUserID($state);

}

# do stuff
if ($uid == 0) {

DoAdminThings();

}

If the application is unable to extract the state information - say, due to a database timeout - then the $uid variable will not be explicitly set by the programmer. This will cause $uid to be regarded as equivalent to "0" in the conditional, allowing the original user to perform administrator actions. Even if the attacker cannot directly influence the state data, unexpected errors could cause incorrect privileges to be assigned to a user just by accident.

Example 3

The following code intends to concatenate a string to a variable and print the string.

(bad code)

Example Language: C

char str[20];
strcat(str, "hello world");
printf("%s", str);

This might seem innocent enough, but str was not initialized, so it contains random memory. As a result, str[0] might not contain the null terminator, so the copy might start at an offset other than 0. The consequences can vary, depending on the underlying memory.

If a null terminator is found before str[8], then some bytes of random garbage will be printed before the "hello world" string. The memory might contain sensitive information from previous uses, such as a password (which might occur as a result of CWE-14 or CWE-244). In this example, it might not be a big deal, but consider what could happen if large amounts of memory are printed out before the null terminator is found.

If a null terminator isn't found before str[8], then a buffer overflow could occur, since strcat will first look for the null terminator, then copy 12 bytes starting with that location. Alternately, a buffer over-read might occur (CWE-126) if a null terminator isn't found before the end of the memory segment is reached, leading to a segmentation fault and crash.

Selected Observed Examples

Reference	Description
CVE-2001-1471	chain: an invalid value prevents a library file from being included, skipping initialization of key variables, leading to resultant eval injection.
CVE-2008-3637	Improper error checking in protection mechanism produces an uninitialized variable, allowing security bypass and code execution.
CVE-2008-4197	Use of uninitialized memory may allow code execution.
CVE-2008-2934	Free of an uninitialized pointer leads to crash and possible code execution.
CVE-2007-3749	OS kernel does not reset a port when starting a setuid program, allowing local users to access the port and gain privileges.
CVE-2008-0063	Product does not clear memory contents when generating an error message, leading to information leak.
CVE-2008-0062	Lack of initialization triggers NULL pointer dereference or double-free.
CVE-2008-0081	Uninitialized variable leads to code execution in popular desktop application.
CVE-2008-3688	chain: Uninitialized variable leads to infinite loop.
CVE-2008-3475	chain: Improper initialization leads to memory corruption.
CVE-2008-5021	Composite: race condition allows attacker to modify an object while it is still being initialized, causing software to access uninitialized memory.
CVE-2005-1036	Chain: Bypass of access restrictions due to improper authorization (CWE-862) of a user results from an improperly initialized (CWE-909) I/O permission bitmap
CVE-2008-3597	chain: game server can access player data structures before initialization has happened leading to NULL dereference
CVE-2009-2692	chain: uninitialized function pointers can be dereferenced allowing code execution
CVE-2009-0949	chain: improper initialization of memory can lead to NULL dereference
CVE-2009-3620	chain: some unprivileged ioctls do not verify that a structure has been initialized before invocation, leading to NULL dereference

Weakness Ordinalities

Ordinality	Description
Primary	(where the weakness exists independent of other weaknesses)
Resultant	(where the weakness is typically related to the presence of some other weaknesses)

Detection Methods

Method	Details
Automated Dynamic Analysis	This weakness can be detected using dynamic tools and techniques that interact with the software using large test suites with many diverse inputs, such as fuzz testing (fuzzing), robustness testing, and fault injection. The software's operation may slow down, but it should not become unstable, crash, or generate incorrect results. Initialization problems may be detected with a stress-test by calling the software simultaneously from a large number of threads or processes, and look for evidence of any unexpected behavior. The software's operation may slow down, but it should not become unstable, crash, or generate incorrect results. Effectiveness: Moderate
Manual Dynamic Analysis	Identify error conditions that are not likely to occur during normal usage and trigger them. For example, run the program under low memory conditions, run with insufficient privileges or permissions, interrupt a transaction before it is completed, or disable connectivity to basic network services such as DNS. Monitor the software for any unexpected behavior. If you trigger an unhandled exception or similar error that was discovered and handled by the application's environment, it may still indicate unexpected conditions that were not handled by the application itself.
Automated Static Analysis	Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.) Effectiveness: High

Memberships

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	740	CERT C Secure Coding Standard (2008) Chapter 7 - Arrays (ARR)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	742	CERT C Secure Coding Standard (2008) Chapter 9 - Memory Management (MEM)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	752	2009 Top 25 - Risky Resource Management
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	846	The CERT Oracle Secure Coding Standard for Java (2011) Chapter 3 - Declarations and Initialization (DCL)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	874	CERT C++ Secure Coding Section 06 - Arrays and the STL (ARR)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	876	CERT C++ Secure Coding Section 08 - Memory Management (MEM)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	962	SFP Secondary Cluster: Unchecked Status Condition
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1135	SEI CERT Oracle Secure Coding Standard for Java - Guidelines 01. Declarations and Initialization (DCL)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1306	CISQ Quality Measures - Reliability
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1308	CISQ Quality Measures - Security
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1340	CISQ Data Protection Measures
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1416	Comprehensive Categorization: Resource Lifecycle Management

Vulnerability Mapping Notes

Usage	DISCOURAGED (this CWE ID should not be used to map to real-world vulnerabilities)
Reason	Abstraction
Rationale	This CWE entry is a level-1 Class (i.e., a child of a Pillar). It might have lower-level children that would be more appropriate
Comments	Examine children of this entry to see if there is a better fit

Taxonomy Mappings

Mapped Taxonomy Name	Node ID	Mapped Node Name
PLOVER		Incorrect initialization
CERT C Secure Coding	ARR02-C	Explicitly specify array bounds, even if implicitly defined by an initializer
The CERT Oracle Secure Coding Standard for Java (2011)	DCL00-J	Prevent class initialization cycles
Software Fault Patterns	SFP4	Unchecked Status Condition

Related Attack Patterns

CAPEC-ID	Attack Pattern Name
CAPEC-26	Leveraging Race Conditions
CAPEC-29	Leveraging Time-of-Check and Time-of-Use (TOCTOU) Race Conditions

References

[REF-436]	mercy. "Exploiting Uninitialized Data". 2006-01. <http://www.felinemenace.org/~mercy/papers/UBehavior/UBehavior.zip>.
[REF-437]	Microsoft Security Vulnerability Research & Defense. "MS08-014 : The Case of the Uninitialized Stack Variable Vulnerability". 2008-03-11. <https://msrc.microsoft.com/blog/2008/03/ms08-014-the-case-of-the-uninitialized-stack-variable-vulnerability/>. (URL validated: 2023-04-07)
[REF-62]	Mark Dowd, John McDonald and Justin Schuh. "The Art of Software Security Assessment". Chapter 7, "Variable Initialization", Page 312. 1st Edition. Addison Wesley. 2006.

Content History

Submissions
Submission Date	Submitter	Organization
2008-04-11 (CWE Draft 9, 2008-04-11)	PLOVER
2008-04-11 (CWE Draft 9, 2008-04-11)
Modifications
Modification Date	Modifier	Organization
2024-02-29 (CWE 4.14, 2024-02-29)	CWE Content Team	MITRE
2024-02-29 (CWE 4.14, 2024-02-29)	updated Mapping_Notes
2023-10-26	CWE Content Team	MITRE
2023-10-26	updated Relationships
2023-06-29	CWE Content Team	MITRE
2023-06-29	updated Mapping_Notes
2023-04-27	CWE Content Team	MITRE
2023-04-27	updated Detection_Factors, References, Relationships
2023-01-31	CWE Content Team	MITRE
2023-01-31	updated Description, Potential_Mitigations, Relationships
2021-03-15	CWE Content Team	MITRE
2021-03-15	updated Observed_Examples
2020-12-10	CWE Content Team	MITRE
2020-12-10	updated Relationships
2020-08-20	CWE Content Team	MITRE
2020-08-20	updated Relationships
2020-06-25	CWE Content Team	MITRE
2020-06-25	updated Relationships
2020-02-24	CWE Content Team	MITRE
2020-02-24	updated Relationships
2019-06-20	CWE Content Team	MITRE
2019-06-20	updated Relationships
2019-01-03	CWE Content Team	MITRE
2019-01-03	updated Related_Attack_Patterns, Relationships, Taxonomy_Mappings
2017-11-08	CWE Content Team	MITRE
2017-11-08	updated References, Taxonomy_Mappings
2017-01-19	CWE Content Team	MITRE
2017-01-19	updated Type
2015-12-07	CWE Content Team	MITRE
2015-12-07	updated Relationships
2014-07-30	CWE Content Team	MITRE
2014-07-30	updated Relationships, Taxonomy_Mappings
2013-02-21	CWE Content Team	MITRE
2013-02-21	updated Demonstrative_Examples, Relationships
2012-05-11	CWE Content Team	MITRE
2012-05-11	updated Demonstrative_Examples, References, Relationships, Taxonomy_Mappings
2011-09-13	CWE Content Team	MITRE
2011-09-13	updated Relationships, Taxonomy_Mappings
2011-06-01	CWE Content Team	MITRE
2011-06-01	updated Common_Consequences, Relationships, Taxonomy_Mappings
2010-09-27	CWE Content Team	MITRE
2010-09-27	updated Observed_Examples
2010-06-21	CWE Content Team	MITRE
2010-06-21	updated Detection_Factors, Potential_Mitigations
2010-04-05	CWE Content Team	MITRE
2010-04-05	updated Applicable_Platforms
2010-02-16	CWE Content Team	MITRE
2010-02-16	updated Potential_Mitigations
2009-10-29	CWE Content Team	MITRE
2009-10-29	updated Common_Consequences
2009-07-27	CWE Content Team	MITRE
2009-07-27	updated Related_Attack_Patterns
2009-05-27	CWE Content Team	MITRE
2009-05-27	updated Description, Relationships
2009-03-10	CWE Content Team	MITRE
2009-03-10	updated Potential_Mitigations
2009-01-12	CWE Content Team	MITRE
2009-01-12	updated Common_Consequences, Demonstrative_Examples, Description, Likelihood_of_Exploit, Modes_of_Introduction, Name, Observed_Examples, Potential_Mitigations, References, Relationships, Weakness_Ordinalities
2008-11-24	CWE Content Team	MITRE
2008-11-24	updated Relationships, Taxonomy_Mappings
2008-09-08	CWE Content Team	MITRE
2008-09-08	updated Relationships, Taxonomy_Mappings
2008-07-01	Eric Dalci	Cigital
2008-07-01	updated Potential_Mitigations, Time_of_Introduction
2008-07-01	Sean Eidemiller	Cigital
2008-07-01	added/updated demonstrative examples
Previous Entry Names
Change Date	Previous Entry Name
2009-01-12	Incorrect or Incomplete Initialization

Weakness ID: 20

View customized information:

Description

The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.

Extended Description

Input validation is a frequently-used technique for checking potentially dangerous inputs in order to ensure that the inputs are safe for processing within the code, or when communicating with other components.

Input can consist of:

raw data - strings, numbers, parameters, file contents, etc.
metadata - information about the raw data, such as headers or size

Data can be simple or structured. Structured data can be composed of many nested layers, composed of combinations of metadata and raw data, with other simple or structured data.

Many properties of raw data or metadata may need to be validated upon entry into the code, such as:

specified quantities such as size, length, frequency, price, rate, number of operations, time, etc.
implied or derived quantities, such as the actual size of a file instead of a specified size
indexes, offsets, or positions into more complex data structures
symbolic keys or other elements into hash tables, associative arrays, etc.
well-formedness, i.e. syntactic correctness - compliance with expected syntax
lexical token correctness - compliance with rules for what is treated as a token
specified or derived type - the actual type of the input (or what the input appears to be)
consistency - between individual data elements, between raw data and metadata, between references, etc.
conformance to domain-specific rules, e.g. business logic
equivalence - ensuring that equivalent inputs are treated the same
authenticity, ownership, or other attestations about the input, e.g. a cryptographic signature to prove the source of the data

Implied or derived properties of data must often be calculated or inferred by the code itself. Errors in deriving properties may be considered a contributing factor to improper input validation.

Common Consequences

Impact	Details
DoS: Crash, Exit, or Restart; DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory)	Scope: Availability An attacker could provide unexpected values and cause a program crash or arbitrary control of resource allocation, leading to excessive consumption of resources such as memory and CPU.
Read Memory; Read Files or Directories	Scope: Confidentiality An attacker could read confidential data if they are able to control resource references.
Modify Memory; Execute Unauthorized Code or Commands	Scope: Integrity, Confidentiality, Availability An attacker could use malicious input to modify data or possibly alter control flow in unexpected ways, including arbitrary command execution.

Potential Mitigations

Phase(s)	Mitigation
Architecture and Design	Strategy: Attack Surface Reduction Consider using language-theoretic security (LangSec) techniques that characterize inputs using a formal language and build "recognizers" for that language. This effectively requires parsing to be a distinct layer that effectively enforces a boundary between raw input and internal data representations, instead of allowing parser code to be scattered throughout the program, where it could be subject to errors or inconsistencies that create weaknesses. [REF-1109] [REF-1110] [REF-1111]
Architecture and Design	Strategy: Libraries or Frameworks Use an input validation framework such as Struts or the OWASP ESAPI Validation API. Note that using a framework does not automatically address all input validation problems; be mindful of weaknesses that could arise from misusing the framework itself (CWE-1173).
Architecture and Design; Implementation	Strategy: Attack Surface Reduction Understand all the potential areas where untrusted inputs can enter the product, including but not limited to: parameters or arguments, cookies, anything read from the network, environment variables, reverse DNS lookups, query results, request headers, URL components, e-mail, files, filenames, databases, and any external systems that provide data to the application. Remember that such inputs may be obtained indirectly through API calls.
Implementation	Strategy: Input Validation Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does. When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue." Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright. Effectiveness: High
Architecture and Design	For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server. Even though client-side checks provide minimal benefits with respect to server-side security, they are still useful. First, they can support intrusion detection. If the server receives input that should have been rejected by the client, then it may be an indication of an attack. Second, client-side error-checking can provide helpful feedback to the user about the expectations for valid input. Third, there may be a reduction in server-side processing time for accidental input errors, although this is typically a small savings.
Implementation	When your application combines data from multiple sources, perform the validation after the sources have been combined. The individual data elements may pass the validation step but violate the intended restrictions after they have been combined.
Implementation	Be especially careful to validate all input when invoking code that crosses language boundaries, such as from an interpreted language to native code. This could create an unexpected interaction between the language boundaries. Ensure that you are not violating any of the expectations of the language with which you are interfacing. For example, even though Java may not be susceptible to buffer overflows, providing a large argument in a call to native code might trigger an overflow.
Implementation	Directly convert your input type into the expected data type, such as using a conversion function that translates a string into a number. After converting to the expected data type, ensure that the input's values fall within the expected range of allowable values and that multi-field consistencies are maintained.
Implementation	Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180, CWE-181). Make sure that your application does not inadvertently decode the same input twice (CWE-174). Such errors could be used to bypass allowlist schemes by introducing dangerous inputs after they have been checked. Use libraries such as the OWASP ESAPI Canonicalization control. Consider performing repeated canonicalization until your input does not change any more. This will avoid double-decoding and similar scenarios, but it might inadvertently modify inputs that are allowed to contain properly-encoded dangerous content.
Implementation	When exchanging data between components, ensure that both components are using the same character encoding. Ensure that the proper encoding is applied at each interface. Explicitly set the encoding you are using whenever the protocol allows you to do so.

Relationships

Relevant to the view "Research Concepts" (View-1000)

Nature	Type	ID	Name
ChildOf	Pillar - a weakness that is the most abstract type of weakness and represents a theme for all class/base/variant weaknesses related to it. A Pillar is different from a Category as a Pillar is still technically a type of weakness that describes a mistake, while a Category represents a common characteristic used to group related things.	707	Improper Neutralization
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	179	Incorrect Behavior Order: Early Validation
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	622	Improper Validation of Function Hook Arguments
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	1173	Improper Use of Validation Framework
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	1284	Improper Validation of Specified Quantity in Input
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	1285	Improper Validation of Specified Index, Position, or Offset in Input
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	1286	Improper Validation of Syntactic Correctness of Input
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	1287	Improper Validation of Specified Type of Input
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	1288	Improper Validation of Consistency within Input
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	1289	Improper Validation of Unsafe Equivalence in Input
PeerOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	345	Insufficient Verification of Data Authenticity
CanPrecede	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	22	Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
CanPrecede	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	41	Improper Resolution of Path Equivalence
CanPrecede	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	74	Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')
CanPrecede	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	119	Improper Restriction of Operations within the Bounds of a Memory Buffer
CanPrecede	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	770	Allocation of Resources Without Limits or Throttling

Relevant to the view "Weaknesses for Simplified Mapping of Published Vulnerabilities" (View-1003)

Nature	Type	ID	Name
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1003	Weaknesses for Simplified Mapping of Published Vulnerabilities
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	129	Improper Validation of Array Index
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	1284	Improper Validation of Specified Quantity in Input

Relevant to the view "Architectural Concepts" (View-1008)

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1019	Validate Inputs

Relevant to the view "Seven Pernicious Kingdoms" (View-700)

Nature	Type	ID	Name
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	15	External Control of System or Configuration Setting
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	73	External Control of File Name or Path
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	102	Struts: Duplicate Validation Forms
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	103	Struts: Incomplete validate() Method Definition
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	104	Struts: Form Bean Does Not Extend Validation Class
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	105	Struts: Form Field Without Validator
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	106	Struts: Plug-in Framework not in Use
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	107	Struts: Unused Validation Form
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	108	Struts: Unvalidated Action Form
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	109	Struts: Validator Turned Off
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	110	Struts: Validator Without Form Field
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	111	Direct Use of Unsafe JNI
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	112	Missing XML Validation
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	113	Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Request/Response Splitting')
ParentOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	114	Process Control
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	117	Improper Output Neutralization for Logs
ParentOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	119	Improper Restriction of Operations within the Bounds of a Memory Buffer
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	120	Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	134	Use of Externally-Controlled Format String
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	170	Improper Null Termination
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	190	Integer Overflow or Wraparound
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	466	Return of Pointer Value Outside of Expected Range
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	470	Use of Externally-Controlled Input to Select Classes or Code ('Unsafe Reflection')
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	785	Use of Path Manipulation Function without Maximum-sized Buffer

Modes Of Introduction

Phase

Note

Architecture and Design

Implementation

REALIZATION: This weakness is caused during implementation of an architectural security tactic.

If a programmer believes that an attacker cannot modify certain inputs, then the programmer might not perform any input validation at all. For example, in web applications, many programmers believe that cookies and hidden form fields can not be modified from a web browser (CWE-472), although they can be altered using a proxy or a custom program. In a client-server architecture, the programmer might assume that client-side security checks cannot be bypassed, even when a custom client could be written that skips those checks (CWE-602).

Applicable Platforms

Languages

Class: Not Language-Specific (Often Prevalent)

Likelihood Of Exploit

High

Demonstrative Examples

Example 1

This example demonstrates a shopping interaction in which the user is free to specify the quantity of items to be purchased and a total is calculated.

(bad code)

Example Language: Java

...
public static final double price = 20.00;
int quantity = currentUser.getAttribute("quantity");
double total = price * quantity;
chargeUser(total);
...

The user has no control over the price variable, however the code does not prevent a negative value from being specified for quantity. If an attacker were to provide a negative value, then the user would have their account credited instead of debited.

Example 2

This example asks the user for a height and width of an m X n game board with a maximum dimension of 100 squares.

(bad code)

Example Language: C

...
#define MAX_DIM 100
...
/* board dimensions */

int m,n, error;
board_square_t *board;
printf("Please specify the board height: \n");
error = scanf("%d", &m);
if ( EOF == error ){

die("No integer passed: Die evil hacker!\n");

}
printf("Please specify the board width: \n");
error = scanf("%d", &n);
if ( EOF == error ){

die("No integer passed: Die evil hacker!\n");

}
if ( m > MAX_DIM || n > MAX_DIM ) {

die("Value too large: Die evil hacker!\n");

}
board = (board_square_t*) malloc( m * n * sizeof(board_square_t));
...

While this code checks to make sure the user cannot specify large, positive integers and consume too much memory, it does not check for negative values supplied by the user. As a result, an attacker can perform a resource consumption (CWE-400) attack against this program by specifying two, large negative values that will not overflow, resulting in a very large memory allocation (CWE-789) and possibly a system crash. Alternatively, an attacker can provide very large negative values which will cause an integer overflow (CWE-190) and unexpected behavior will follow depending on how the values are treated in the remainder of the program.

Example 3

The following example shows a PHP application in which the programmer attempts to display a user's birthday and homepage.

(bad code)

Example Language: PHP

$birthday = $_GET['birthday'];
$homepage = $_GET['homepage'];
echo "Birthday: $birthday<br>Homepage: <a href=$homepage>click here</a>"

The programmer intended for $birthday to be in a date format and $homepage to be a valid URL. However, since the values are derived from an HTTP request, if an attacker can trick a victim into clicking a crafted URL with <script> tags providing the values for birthday and / or homepage, then the script will run on the client's browser when the web server echoes the content. Notice that even if the programmer were to defend the $birthday variable by restricting input to integers and dashes, it would still be possible for an attacker to provide a string of the form:

(attack code)

2009-01-09--

If this data were used in a SQL statement, it would treat the remainder of the statement as a comment. The comment could disable other security-related logic in the statement. In this case, encoding combined with input validation would be a more useful protection mechanism.

Furthermore, an XSS (CWE-79) attack or SQL injection (CWE-89) are just a few of the potential consequences when input validation is not used. Depending on the context of the code, CRLF Injection (CWE-93), Argument Injection (CWE-88), or Command Injection (CWE-77) may also be possible.

Example 4

The following example takes a user-supplied value to allocate an array of objects and then operates on the array.

(bad code)

Example Language: Java

private void buildList ( int untrustedListSize ){

if ( 0 > untrustedListSize ){

die("Negative value supplied for list size, die evil hacker!");

}
Widget[] list = new Widget [ untrustedListSize ];
list[0] = new Widget();

}

This example attempts to build a list from a user-specified value, and even checks to ensure a non-negative value is supplied. If, however, a 0 value is provided, the code will build an array of size 0 and then try to store a new Widget in the first location, causing an exception to be thrown.

Example 5

This Android application has registered to handle a URL when sent an intent:

(bad code)

Example Language: Java

...
IntentFilter filter = new IntentFilter("com.example.URLHandler.openURL");
MyReceiver receiver = new MyReceiver();
registerReceiver(receiver, filter);
...

public class UrlHandlerReceiver extends BroadcastReceiver {

@Override
public void onReceive(Context context, Intent intent) {

if("com.example.URLHandler.openURL".equals(intent.getAction())) {

String URL = intent.getStringExtra("URLToOpen");
int length = URL.length();

...
}

}

The application assumes the URL will always be included in the intent. When the URL is not present, the call to getStringExtra() will return null, thus causing a null pointer exception when length() is called.

Selected Observed Examples

Reference	Description
CVE-2024-37032	Large language model (LLM) management tool does not validate the format of a digest value (CWE-1287) from a private, untrusted model registry, enabling relative path traversal (CWE-23), a.k.a. Probllama
CVE-2022-45918	Chain: a learning management tool debugger uses external input to locate previous session logs (CWE-73) and does not properly validate the given path (CWE-20), allowing for filesystem path traversal using "../" sequences (CWE-24)
CVE-2021-30860	Chain: improper input validation (CWE-20) leads to integer overflow (CWE-190) in mobile OS, as exploited in the wild per CISA KEV.
CVE-2021-30663	Chain: improper input validation (CWE-20) leads to integer overflow (CWE-190) in mobile OS, as exploited in the wild per CISA KEV.
CVE-2021-22205	Chain: backslash followed by a newline can bypass a validation step (CWE-20), leading to eval injection (CWE-95), as exploited in the wild per CISA KEV.
CVE-2021-21220	Chain: insufficient input validation (CWE-20) in browser allows heap corruption (CWE-787), as exploited in the wild per CISA KEV.
CVE-2020-9054	Chain: improper input validation (CWE-20) in username parameter, leading to OS command injection (CWE-78), as exploited in the wild per CISA KEV.
CVE-2020-3452	Chain: security product has improper input validation (CWE-20) leading to directory traversal (CWE-22), as exploited in the wild per CISA KEV.
CVE-2020-3161	Improper input validation of HTTP requests in IP phone, as exploited in the wild per CISA KEV.
CVE-2020-3580	Chain: improper input validation (CWE-20) in firewall product leads to XSS (CWE-79), as exploited in the wild per CISA KEV.
CVE-2021-37147	Chain: caching proxy server has improper input validation (CWE-20) of headers, allowing HTTP response smuggling (CWE-444) using an "LF line ending"
CVE-2008-5305	Eval injection in Perl program using an ID that should only contain hyphens and numbers.
CVE-2008-2223	SQL injection through an ID that was supposed to be numeric.
CVE-2008-3477	lack of input validation in spreadsheet program leads to buffer overflows, integer overflows, array index errors, and memory corruption.
CVE-2008-3843	insufficient validation enables XSS
CVE-2008-3174	driver in security product allows code execution due to insufficient validation
CVE-2007-3409	infinite loop from DNS packet with a label that points to itself
CVE-2006-6870	infinite loop from DNS packet with a label that points to itself
CVE-2008-1303	missing parameter leads to crash
CVE-2007-5893	HTTP request with missing protocol version number leads to crash
CVE-2006-6658	request with missing parameters leads to information exposure
CVE-2008-4114	system crash with offset value that is inconsistent with packet size
CVE-2006-3790	size field that is inconsistent with packet size leads to buffer over-read
CVE-2008-2309	product uses a denylist to identify potentially dangerous content, allowing attacker to bypass a warning
CVE-2008-3494	security bypass via an extra header
CVE-2008-3571	empty packet triggers reboot
CVE-2006-5525	incomplete denylist allows SQL injection
CVE-2008-1284	NUL byte in theme name causes directory traversal impact to be worse
CVE-2008-0600	kernel does not validate an incoming pointer before dereferencing it
CVE-2008-1738	anti-virus product has insufficient input validation of hooked SSDT functions, allowing code execution
CVE-2008-1737	anti-virus product allows DoS via zero-length field
CVE-2008-3464	driver does not validate input from userland to the kernel
CVE-2008-2252	kernel does not validate parameters sent in from userland, allowing code execution
CVE-2008-2374	lack of validation of string length fields allows memory consumption or buffer over-read
CVE-2008-1440	lack of validation of length field leads to infinite loop
CVE-2008-1625	lack of validation of input to an IOCTL allows code execution
CVE-2008-3177	zero-length attachment causes crash
CVE-2007-2442	zero-length input causes free of uninitialized pointer
CVE-2008-5563	crash via a malformed frame structure
CVE-2008-5285	infinite loop from a long SMTP request
CVE-2008-3812	router crashes with a malformed packet
CVE-2008-3680	packet with invalid version number leads to NULL pointer dereference
CVE-2008-3660	crash via multiple "." characters in file extension

Detection Methods

Method	Details
Automated Static Analysis	Some instances of improper input validation can be detected using automated static analysis. A static analysis tool might allow the user to specify which application-specific methods or functions perform input validation; the tool might also have built-in knowledge of validation frameworks such as Struts. The tool may then suppress or de-prioritize any associated warnings. This allows the analyst to focus on areas of the software in which input validation does not appear to be present. Except in the cases described in the previous paragraph, automated static analysis might not be able to recognize when proper input validation is being performed, leading to false positives - i.e., warnings that do not have any security consequences or require any code changes.
Manual Static Analysis	When custom input validation is required, such as when enforcing business rules, manual analysis is necessary to ensure that the validation is properly implemented.
Fuzzing	Fuzzing techniques can be useful for detecting input validation errors. When unexpected inputs are provided to the software, the software should not crash or otherwise become unstable, and it should generate application-controlled error messages. If exceptions or interpreter-generated error messages occur, this indicates that the input was not detected and handled within the application logic itself.
Automated Static Analysis - Binary or Bytecode	According to SOAR, the following detection techniques may be useful: Cost effective for partial coverage: Bytecode Weakness Analysis - including disassembler + source code weakness analysis Binary Weakness Analysis - including disassembler + source code weakness analysis Effectiveness: SOAR Partial
Manual Static Analysis - Binary or Bytecode	According to SOAR, the following detection techniques may be useful: Cost effective for partial coverage: Binary / Bytecode disassembler - then use manual analysis for vulnerabilities & anomalies Effectiveness: SOAR Partial
Dynamic Analysis with Automated Results Interpretation	According to SOAR, the following detection techniques may be useful: Highly cost effective: Web Application Scanner Web Services Scanner Database Scanners Effectiveness: High
Dynamic Analysis with Manual Results Interpretation	According to SOAR, the following detection techniques may be useful: Highly cost effective: Fuzz Tester Framework-based Fuzzer Cost effective for partial coverage: Host Application Interface Scanner Monitored Virtual Environment - run potentially malicious code in sandbox / wrapper / virtual machine, see if it does anything suspicious Effectiveness: High
Manual Static Analysis - Source Code	According to SOAR, the following detection techniques may be useful: Highly cost effective: Focused Manual Spotcheck - Focused manual analysis of source Manual Source Code Review (not inspections) Effectiveness: High
Automated Static Analysis - Source Code	According to SOAR, the following detection techniques may be useful: Highly cost effective: Source code Weakness Analyzer Context-configured Source Code Weakness Analyzer Effectiveness: High
Architecture or Design Review	According to SOAR, the following detection techniques may be useful: Highly cost effective: Inspection (IEEE 1028 standard) (can apply to requirements, design, source code, etc.) Formal Methods / Correct-By-Construction Cost effective for partial coverage: Attack Modeling Effectiveness: High

Memberships

Nature	Type	ID	Name
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	635	Weaknesses Originally Used by NVD from 2008 to 2016
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	722	OWASP Top Ten 2004 Category A1 - Unvalidated Input
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	738	CERT C Secure Coding Standard (2008) Chapter 5 - Integers (INT)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	742	CERT C Secure Coding Standard (2008) Chapter 9 - Memory Management (MEM)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	746	CERT C Secure Coding Standard (2008) Chapter 13 - Error Handling (ERR)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	747	CERT C Secure Coding Standard (2008) Chapter 14 - Miscellaneous (MSC)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	751	2009 Top 25 - Insecure Interaction Between Components
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	872	CERT C++ Secure Coding Section 04 - Integers (INT)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	876	CERT C++ Secure Coding Section 08 - Memory Management (MEM)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	883	CERT C++ Secure Coding Section 49 - Miscellaneous (MSC)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	994	SFP Secondary Cluster: Tainted Input to Variable
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1005	7PK - Input Validation and Representation
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1163	SEI CERT C Coding Standard - Guidelines 09. Input Output (FIO)
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1200	Weaknesses in the 2019 CWE Top 25 Most Dangerous Software Errors
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1337	Weaknesses in the 2021 CWE Top 25 Most Dangerous Software Weaknesses
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1347	OWASP Top Ten 2021 Category A03:2021 - Injection
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1350	Weaknesses in the 2020 CWE Top 25 Most Dangerous Software Weaknesses
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1382	ICS Operations (& Maintenance): Emerging Energy Technologies
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1387	Weaknesses in the 2022 CWE Top 25 Most Dangerous Software Weaknesses
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1406	Comprehensive Categorization: Improper Input Validation
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1425	Weaknesses in the 2023 CWE Top 25 Most Dangerous Software Weaknesses
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1430	Weaknesses in the 2024 CWE Top 25 Most Dangerous Software Weaknesses

Vulnerability Mapping Notes

Usage

DISCOURAGED

(this CWE ID should not be used to map to real-world vulnerabilities)

Reasons

Frequent Misuse, Frequent Misinterpretation, Abstraction

Rationale

CWE-20 is commonly misused in low-information vulnerability reports when lower-level CWEs could be used instead, or when more details about the vulnerability are available [REF-1287]. It is not useful for trend analysis. It is also a level-1 Class (i.e., a child of a Pillar). Finally, it is often used when the root cause issue is related to how input is incorrectly transformed, instead of "validated" to be correct as-is.

Comments

Within CWE, the "input validation" term focuses on the act of checking whether an input is already safe, which is different from other techniques that ensure safe processing of input. Carefully perform root-cause analysis to be sure that the issue is not due to techniques that attempt to transform potentially-dangerous input into something safe, such as filtering (CWE-790) - which attempts to remove dangerous inputs - or encoding/escaping (CWE-116), which attempts to ensure that the input is not misinterpreted when it is included in output to another component. If the issue is truly due to imroper input validation, consider using lower-level children such as Improper Use of Validation Framework (CWE-1173) or improper validation involving specific types or properties of input such as Specified Quantity (CWE-1284); Specified Index, Position, or Offset (CWE-1285); Syntactic Correctness (CWE-1286); Specified Type (CWE-1287); Consistency within Input (CWE-1288); or Unsafe Equivalence (CWE-1289).

Suggestions

CWE-ID	Comment
CWE-1284	Specified Quantity
CWE-1285	Specified Index, Position, or Offset
CWE-1286	Syntactic Correctness
CWE-1287	Specified Type
CWE-1288	Consistency within Input
CWE-1289	Unsafe Equivalence
CWE-116	Improper Encoding or Escaping of Output
CWE-790	Improper Filtering of Special Elements

Notes

Relationship

Multiple techniques exist to transform potentially dangerous input into something safe, which is different than "validation," which is a technique to check if an input is already safe. CWE users need to be cautious during root cause analysis to ensure that an issue is truly an input-validation problem.

Terminology

The "input validation" term is extremely common, but it is used in many different ways. In some cases its usage can obscure the real underlying weakness or otherwise hide chaining and composite relationships.

Some people use "input validation" as a general term that covers many different neutralization techniques for ensuring that input is appropriate, such as filtering, i.e., attempting to remove dangerous inputs (related to CWE-790); encoding/escaping, i.e., attempting to ensure that the input is not misinterpreted when it is included in output to another component (related to CWE-116); or canonicalization, which often indirectly removes otherwise-dangerous inputs. Others use the term in a narrower context to simply mean "checking if an input conforms to expectations without changing it." CWE uses this narrow interpretation.

Note that "input validation" has very different meanings to different people, or within different classification schemes. Caution must be used when referencing this CWE entry or mapping to it. For example, some weaknesses might involve inadvertently giving control to an attacker over an input when they should not be able to provide an input at all, but sometimes this is referred to as input validation.

Finally, it is important to emphasize that the distinctions between input validation and output escaping are often blurred. Developers must be careful to understand the difference, including how input validation is not always sufficient to prevent vulnerabilities, especially when less stringent data types must be supported, such as free-form text. Consider a SQL injection scenario in which a person's last name is inserted into a query. The name "O'Reilly" would likely pass the validation step since it is a common last name in the English language. However, this valid name cannot be directly inserted into the database because it contains the "'" apostrophe character, which would need to be escaped or otherwise transformed. In this case, removing the apostrophe might reduce the risk of SQL injection, but it would produce incorrect behavior because the wrong name would be recorded.

Maintenance

As of 2020, this entry is used more often than preferred, and it is a source of frequent confusion. It is being actively modified for CWE 4.1 and subsequent versions.

Maintenance

Concepts such as validation, data transformation, and neutralization are being refined, so relationships between CWE-20 and other entries such as CWE-707 may change in future versions, along with an update to the Vulnerability Theory document.

Maintenance

Input validation - whether missing or incorrect - is such an essential and widespread part of secure development that it is implicit in many different weaknesses. Traditionally, problems such as buffer overflows and XSS have been classified as input validation problems by many security professionals. However, input validation is not necessarily the only protection mechanism available for avoiding such problems, and in some cases it is not even sufficient. The CWE team has begun capturing these subtleties in chains within the Research Concepts view (CWE-1000), but more work is needed.

Taxonomy Mappings

Mapped Taxonomy Name	Node ID	Fit	Mapped Node Name
7 Pernicious Kingdoms			Input validation and representation
OWASP Top Ten 2004	A1	CWE More Specific	Unvalidated Input
CERT C Secure Coding	ERR07-C		Prefer functions that support error checking over equivalent functions that don't
CERT C Secure Coding	FIO30-C	CWE More Abstract	Exclude user input from format strings
CERT C Secure Coding	MEM10-C		Define and use a pointer validation function
WASC	20		Improper Input Handling
Software Fault Patterns	SFP25		Tainted input to variable

Related Attack Patterns

CAPEC-ID	Attack Pattern Name
CAPEC-10	Buffer Overflow via Environment Variables
CAPEC-101	Server Side Include (SSI) Injection
CAPEC-104	Cross Zone Scripting
CAPEC-108	Command Line Execution through SQL Injection
CAPEC-109	Object Relational Mapping Injection
CAPEC-110	SQL Injection through SOAP Parameter Tampering
CAPEC-120	Double Encoding
CAPEC-13	Subverting Environment Variable Values
CAPEC-135	Format String Injection
CAPEC-136	LDAP Injection
CAPEC-14	Client-side Injection-induced Buffer Overflow
CAPEC-153	Input Data Manipulation
CAPEC-182	Flash Injection
CAPEC-209	XSS Using MIME Type Mismatch
CAPEC-22	Exploiting Trust in Client
CAPEC-23	File Content Injection
CAPEC-230	Serialized Data with Nested Payloads
CAPEC-231	Oversized Serialized Data Payloads
CAPEC-24	Filter Failure through Buffer Overflow
CAPEC-250	XML Injection
CAPEC-261	Fuzzing for garnering other adjacent user/sensitive data
CAPEC-267	Leverage Alternate Encoding
CAPEC-28	Fuzzing
CAPEC-3	Using Leading 'Ghost' Character Sequences to Bypass Input Filters
CAPEC-31	Accessing/Intercepting/Modifying HTTP Cookies
CAPEC-42	MIME Conversion
CAPEC-43	Exploiting Multiple Input Interpretation Layers
CAPEC-45	Buffer Overflow via Symbolic Links
CAPEC-46	Overflow Variables and Tags
CAPEC-47	Buffer Overflow via Parameter Expansion
CAPEC-473	Signature Spoof
CAPEC-52	Embedding NULL Bytes
CAPEC-53	Postfix, Null Terminate, and Backslash
CAPEC-588	DOM-Based XSS
CAPEC-63	Cross-Site Scripting (XSS)
CAPEC-64	Using Slashes and URL Encoding Combined to Bypass Validation Logic
CAPEC-664	Server Side Request Forgery
CAPEC-67	String Format Overflow in syslog()
CAPEC-7	Blind SQL Injection
CAPEC-71	Using Unicode Encoding to Bypass Validation Logic
CAPEC-72	URL Encoding
CAPEC-73	User-Controlled Filename
CAPEC-78	Using Escaped Slashes in Alternate Encoding
CAPEC-79	Using Slashes in Alternate Encoding
CAPEC-8	Buffer Overflow in an API Call
CAPEC-80	Using UTF-8 Encoding to Bypass Validation Logic
CAPEC-81	Web Server Logs Tampering
CAPEC-83	XPath Injection
CAPEC-85	AJAX Footprinting
CAPEC-88	OS Command Injection
CAPEC-9	Buffer Overflow in Local Command-Line Utilities

References

[REF-6]	Katrina Tsipenyuk, Brian Chess and Gary McGraw. "Seven Pernicious Kingdoms: A Taxonomy of Software Security Errors". NIST Workshop on Software Security Assurance Tools Techniques and Metrics. NIST. 2005-11-07. <https://samate.nist.gov/SSATTM_Content/papers/Seven%20Pernicious%20Kingdoms%20-%20Taxonomy%20of%20Sw%20Security%20Errors%20-%20Tsipenyuk%20-%20Chess%20-%20McGraw.pdf>.
[REF-166]	Jim Manico. "Input Validation with ESAPI - Very Important". 2008-08-15. <https://manicode.blogspot.com/2008/08/input-validation-with-esapi.html>. (URL validated: 2023-04-07)
[REF-45]	OWASP. "OWASP Enterprise Security API (ESAPI) Project". <http://www.owasp.org/index.php/ESAPI>.
[REF-168]	Joel Scambray, Mike Shema and Caleb Sima. "Hacking Exposed Web Applications, Second Edition". Input Validation Attacks. McGraw-Hill. 2006-06-05.
[REF-48]	Jeremiah Grossman. "Input validation or output filtering, which is better?". 2007-01-30. <https://blog.jeremiahgrossman.com/2007/01/input-validation-or-output-filtering.html>. (URL validated: 2023-04-07)
[REF-170]	Kevin Beaver. "The importance of input validation". 2006-09-06. <http://searchsoftwarequality.techtarget.com/tip/0,289483,sid92_gci1214373,00.html>.
[REF-7]	Michael Howard and David LeBlanc. "Writing Secure Code". Chapter 10, "All Input Is Evil!" Page 341. 2nd Edition. Microsoft Press. 2002-12-04. <https://www.microsoftpressstore.com/store/writing-secure-code-9780735617223>.
[REF-1109]	"LANGSEC: Language-theoretic Security". <http://langsec.org/>.
[REF-1110]	"LangSec: Recognition, Validation, and Compositional Correctness for Real World Security". <http://langsec.org/bof-handout.pdf>.
[REF-1111]	Sergey Bratus, Lars Hermerschmidt, Sven M. Hallberg, Michael E. Locasto, Falcon D. Momot, Meredith L. Patterson and Anna Shubina. "Curing the Vulnerable Parser: Design Patterns for Secure Input Handling". USENIX ;login:. 2017. <https://www.usenix.org/system/files/login/articles/login_spring17_08_bratus.pdf>.
[REF-1287]	MITRE. "Supplemental Details - 2022 CWE Top 25". Details of Problematic Mappings. 2022-06-28. <https://cwe.mitre.org/top25/archive/2022/2022_cwe_top25_supplemental.html#problematicMappingDetails>. (URL validated: 2024-11-17)

Content History

Submissions
Submission Date	Submitter	Organization
2006-07-19 (CWE Draft 3, 2006-07-19)	7 Pernicious Kingdoms
2006-07-19 (CWE Draft 3, 2006-07-19)
Contributions
Contribution Date	Contributor	Organization
2024-02-29 (CWE 4.17, 2025-04-03)	Abhi Balakrishnan
2024-02-29 (CWE 4.17, 2025-04-03)	Contributed usability diagram concepts used by the CWE team.
Modifications
Modification Date	Modifier	Organization
2025-04-03 (CWE 4.17, 2025-04-03)	CWE Content Team	MITRE
2025-04-03 (CWE 4.17, 2025-04-03)	updated Common_Consequences, Description, Diagram, Mapping_Notes, Potential_Mitigations, Relationship_Notes, Terminology_Notes
2024-11-19 (CWE 4.16, 2024-11-19)	CWE Content Team	MITRE
2024-11-19 (CWE 4.16, 2024-11-19)	updated Relationships
2024-07-16 (CWE 4.15, 2024-07-16)	CWE Content Team	MITRE
2024-07-16 (CWE 4.15, 2024-07-16)	updated Observed_Examples
2023-10-26	CWE Content Team	MITRE
2023-10-26	updated Observed_Examples
2023-06-29	CWE Content Team	MITRE
2023-06-29	updated Mapping_Notes, Relationships
2023-04-27	CWE Content Team	MITRE
2023-04-27	updated References, Relationships
2022-10-13	CWE Content Team	MITRE
2022-10-13	updated References, Relationships
2022-06-28	CWE Content Team	MITRE
2022-06-28	updated Observed_Examples, Relationships
2022-04-28	CWE Content Team	MITRE
2022-04-28	updated Relationships
2021-10-28	CWE Content Team	MITRE
2021-10-28	updated Relationships
2021-07-20	CWE Content Team	MITRE
2021-07-20	updated Related_Attack_Patterns, Relationships
2021-03-15	CWE Content Team	MITRE
2021-03-15	updated Description, Potential_Mitigations
2020-08-20	CWE Content Team	MITRE
2020-08-20	updated Potential_Mitigations, Related_Attack_Patterns, Relationships
2020-06-25	CWE Content Team	MITRE
2020-06-25	updated Applicable_Platforms, Demonstrative_Examples, Description, Maintenance_Notes, Observed_Examples, Potential_Mitigations, References, Relationship_Notes, Relationships, Research_Gaps, Terminology_Notes
2020-02-24	CWE Content Team	MITRE
2020-02-24	updated Potential_Mitigations, References, Related_Attack_Patterns, Relationships
2019-09-19	CWE Content Team	MITRE
2019-09-19	updated Relationships
2019-06-20	CWE Content Team	MITRE
2019-06-20	updated Related_Attack_Patterns, Relationships
2019-01-03	CWE Content Team	MITRE
2019-01-03	updated Related_Attack_Patterns, Relationships
2018-03-27	CWE Content Team	MITRE
2018-03-27	updated References
2017-11-08	CWE Content Team	MITRE
2017-11-08	updated Modes_of_Introduction, References, Relationships, Taxonomy_Mappings
2017-05-03	CWE Content Team	MITRE
2017-05-03	updated Related_Attack_Patterns, Relationships
2017-01-19	CWE Content Team	MITRE
2017-01-19	updated Related_Attack_Patterns, Relationships
2015-12-07	CWE Content Team	MITRE
2015-12-07	updated Relationships
2014-07-30	CWE Content Team	MITRE
2014-07-30	updated Detection_Factors, Relationships, Taxonomy_Mappings
2014-02-18	CWE Content Team	MITRE
2014-02-18	updated Demonstrative_Examples, Related_Attack_Patterns
2013-07-17	CWE Content Team	MITRE
2013-07-17	updated Relationships
2013-02-21	CWE Content Team	MITRE
2013-02-21	updated Relationships
2012-10-30	CWE Content Team	MITRE
2012-10-30	updated Potential_Mitigations
2012-05-11	CWE Content Team	MITRE
2012-05-11	updated Demonstrative_Examples, References, Related_Attack_Patterns, Relationships
2011-09-13	CWE Content Team	MITRE
2011-09-13	updated Relationships, Taxonomy_Mappings
2011-06-01	CWE Content Team	MITRE
2011-06-01	updated Applicable_Platforms, Common_Consequences, Relationship_Notes
2011-03-29	CWE Content Team	MITRE
2011-03-29	updated Observed_Examples
2010-12-13	CWE Content Team	MITRE
2010-12-13	updated Demonstrative_Examples, Description
2010-09-27	CWE Content Team	MITRE
2010-09-27	updated Potential_Mitigations, Relationships
2010-06-21	CWE Content Team	MITRE
2010-06-21	updated Potential_Mitigations, Research_Gaps, Terminology_Notes
2010-04-05	CWE Content Team	MITRE
2010-04-05	updated Related_Attack_Patterns
2010-02-16	CWE Content Team	MITRE
2010-02-16	updated Detection_Factors, Potential_Mitigations, References, Taxonomy_Mappings
2009-12-28	CWE Content Team	MITRE
2009-12-28	updated Applicable_Platforms, Demonstrative_Examples, Detection_Factors
2009-10-29	CWE Content Team	MITRE
2009-10-29	updated Common_Consequences, Demonstrative_Examples, Maintenance_Notes, Modes_of_Introduction, Observed_Examples, Relationships, Research_Gaps, Terminology_Notes
2009-07-27	CWE Content Team	MITRE
2009-07-27	updated Relationships
2009-05-27	CWE Content Team	MITRE
2009-05-27	updated Related_Attack_Patterns
2009-03-10	CWE Content Team	MITRE
2009-03-10	updated Description, Potential_Mitigations
2009-01-12	CWE Content Team	MITRE
2009-01-12	updated Applicable_Platforms, Common_Consequences, Demonstrative_Examples, Description, Likelihood_of_Exploit, Name, Observed_Examples, Other_Notes, Potential_Mitigations, References, Relationship_Notes, Relationships
2008-11-24	CWE Content Team	MITRE
2008-11-24	updated Relationships, Taxonomy_Mappings
2008-09-08	CWE Content Team	MITRE
2008-09-08	updated Relationships, Other_Notes, Taxonomy_Mappings
2008-08-15		Veracode
2008-08-15	Suggested OWASP Top Ten 2004 mapping
2008-07-01	Eric Dalci	Cigital
2008-07-01	updated Potential_Mitigations, Time_of_Introduction
Previous Entry Names
Change Date	Previous Entry Name
2009-01-12	Insufficient Input Validation

Weakness ID: 22

View customized information:

Description

Extended Description

Many file operations are intended to take place within a restricted directory. By using special elements such as ".." and "/" separators, attackers can escape outside of the restricted location to access files or directories that are elsewhere on the system. One of the most common special elements is the "../" sequence, which in most modern operating systems is interpreted as the parent directory of the current location. This is referred to as relative path traversal. Path traversal also covers the use of absolute pathnames such as "/usr/local/bin" to access unexpected files. This is referred to as absolute path traversal.

Alternate Terms

Directory traversal
Path traversal	"Path traversal" is preferred over "directory traversal," but both terms are attack-focused.

Common Consequences

Impact	Details
Execute Unauthorized Code or Commands	Scope: Integrity, Confidentiality, Availability The attacker may be able to create or overwrite critical files that are used to execute code, such as programs or libraries.
Modify Files or Directories	Scope: Integrity The attacker may be able to overwrite or create critical files, such as programs, libraries, or important data. If the targeted file is used for a security mechanism, then the attacker may be able to bypass that mechanism. For example, appending a new account at the end of a password file may allow an attacker to bypass authentication.
Read Files or Directories	Scope: Confidentiality The attacker may be able read the contents of unexpected files and expose sensitive data. If the targeted file is used for a security mechanism, then the attacker may be able to bypass that mechanism. For example, by reading a password file, the attacker could conduct brute force password guessing attacks in order to break into an account on the system.
DoS: Crash, Exit, or Restart	Scope: Availability The attacker may be able to overwrite, delete, or corrupt unexpected critical files such as programs, libraries, or important data. This may prevent the product from working at all and in the case of protection mechanisms such as authentication, it has the potential to lock out product users.

Potential Mitigations

Phase(s)	Mitigation
Implementation	Strategy: Input Validation Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does. When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue." Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright. When validating filenames, use stringent allowlists that limit the character set to be used. If feasible, only allow a single "." character in the filename to avoid weaknesses such as CWE-23, and exclude directory separators such as "/" to avoid CWE-36. Use a list of allowable file extensions, which will help to avoid CWE-434. Do not rely exclusively on a filtering mechanism that removes potentially dangerous characters. This is equivalent to a denylist, which may be incomplete (CWE-184). For example, filtering "/" is insufficient protection if the filesystem also supports the use of "\" as a directory separator. Another possible error could occur when the filtering is applied in a way that still produces dangerous data (CWE-182). For example, if "../" sequences are removed from the ".../...//" string in a sequential fashion, two instances of "../" would be removed from the original string, but the remaining characters would still form the "../" string.
Architecture and Design	For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.
Implementation	Strategy: Input Validation Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180). Make sure that the application does not decode the same input twice (CWE-174). Such errors could be used to bypass allowlist validation schemes by introducing dangerous inputs after they have been checked. Use a built-in path canonicalization function (such as realpath() in C) that produces the canonical version of the pathname, which effectively removes ".." sequences and symbolic links (CWE-23, CWE-59). This includes: realpath() in C getCanonicalPath() in Java GetFullPath() in ASP.NET realpath() or abs_path() in Perl realpath() in PHP
Architecture and Design	Strategy: Libraries or Frameworks Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
Operation	Strategy: Firewall Use an application firewall that can detect attacks against this weakness. It can be beneficial in cases in which the code cannot be fixed (because it is controlled by a third party), as an emergency prevention measure while more comprehensive software assurance measures are applied, or to provide defense in depth. Effectiveness: Moderate Note: An application firewall might not cover all possible input vectors. In addition, attack techniques might be available to bypass the protection mechanism, such as using malformed inputs that can still be processed by the component that receives those inputs. Depending on functionality, an application firewall might inadvertently reject or modify legitimate requests. Finally, some manual effort may be required for customization.
Architecture and Design; Operation	Strategy: Environment Hardening Run your code using the lowest privileges that are required to accomplish the necessary tasks [REF-76]. If possible, create isolated accounts with limited privileges that are only used for a single task. That way, a successful attack will not immediately give the attacker access to the rest of the software or its environment. For example, database applications rarely need to run as the database administrator, especially in day-to-day operations.
Architecture and Design	Strategy: Enforcement by Conversion When the set of acceptable objects, such as filenames or URLs, is limited or known, create a mapping from a set of fixed input values (such as numeric IDs) to the actual filenames or URLs, and reject all other inputs. For example, ID 1 could map to "inbox.txt" and ID 2 could map to "profile.txt". Features such as the ESAPI AccessReferenceMap [REF-185] provide this capability.
Architecture and Design; Operation	Strategy: Sandbox or Jail Run the code in a "jail" or similar sandbox environment that enforces strict boundaries between the process and the operating system. This may effectively restrict which files can be accessed in a particular directory or which commands can be executed by the software. OS-level examples include the Unix chroot jail, AppArmor, and SELinux. In general, managed code may provide some protection. For example, java.io.FilePermission in the Java SecurityManager allows the software to specify restrictions on file operations. This may not be a feasible solution, and it only limits the impact to the operating system; the rest of the application may still be subject to compromise. Be careful to avoid CWE-243 and other weaknesses related to jails. Effectiveness: Limited Note: The effectiveness of this mitigation depends on the prevention capabilities of the specific sandbox or jail being used and might only help to reduce the scope of an attack, such as restricting the attacker to certain system calls or limiting the portion of the file system that can be accessed.
Architecture and Design; Operation	Strategy: Attack Surface Reduction Store library, include, and utility files outside of the web document root, if possible. Otherwise, store them in a separate directory and use the web server's access control capabilities to prevent attackers from directly requesting them. One common practice is to define a fixed constant in each calling program, then check for the existence of the constant in the library/include file; if the constant does not exist, then the file was directly requested, and it can exit immediately. This significantly reduces the chance of an attacker being able to bypass any protection mechanisms that are in the base program but not in the include files. It will also reduce the attack surface.
Implementation	Ensure that error messages only contain minimal details that are useful to the intended audience and no one else. The messages need to strike the balance between being too cryptic (which can confuse users) or being too detailed (which may reveal more than intended). The messages should not reveal the methods that were used to determine the error. Attackers can use detailed information to refine or optimize their original attack, thereby increasing their chances of success. If errors must be captured in some detail, record them in log messages, but consider what could occur if the log messages can be viewed by attackers. Highly sensitive information such as passwords should never be saved to log files. Avoid inconsistent messaging that might accidentally tip off an attacker about internal state, such as whether a user account exists or not. In the context of path traversal, error messages which disclose path information can help attackers craft the appropriate attack strings to move through the file system hierarchy.
Operation; Implementation	Strategy: Environment Hardening When using PHP, configure the application so that it does not use register_globals. During implementation, develop the application so that it does not rely on this feature, but be wary of implementing a register_globals emulation that is subject to weaknesses such as CWE-95, CWE-621, and similar issues.

Relationships

Relevant to the view "Research Concepts" (View-1000)

Nature	Type	ID	Name
ChildOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	706	Use of Incorrectly-Resolved Name or Reference
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	23	Relative Path Traversal
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	36	Absolute Path Traversal
CanFollow	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	20	Improper Input Validation
CanFollow	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	73	External Control of File Name or Path
CanFollow	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	172	Encoding Error
CanPrecede	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	668	Exposure of Resource to Wrong Sphere

Relevant to the view "Software Development" (View-699)

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1219	File Handling Issues

Relevant to the view "Weaknesses for Simplified Mapping of Published Vulnerabilities" (View-1003)

Nature	Type	ID	Name
ChildOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	706	Use of Incorrectly-Resolved Name or Reference

Relevant to the view "CISQ Quality Measures (2020)" (View-1305)

Nature	Type	ID	Name
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	23	Relative Path Traversal
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	36	Absolute Path Traversal

Relevant to the view "CISQ Data Protection Measures" (View-1340)

Nature	Type	ID	Name
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	23	Relative Path Traversal
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	36	Absolute Path Traversal

Modes Of Introduction

Phase	Note
Implementation

Applicable Platforms

Languages

Class: Not Language-Specific (Undetermined Prevalence)

Likelihood Of Exploit

High

Demonstrative Examples

Example 1

The following code could be for a social networking application in which each user's profile information is stored in a separate file. All files are stored in a single directory.

(bad code)

Example Language: Perl

my $dataPath = "/users/cwe/profiles";
my $username = param("user");
my $profilePath = $dataPath . "/" . $username;

open(my $fh, "<", $profilePath) || ExitError("profile read error: $profilePath");
print "<ul>\n";
while (<$fh>) {

print "<li>$_</li>\n";

}
print "</ul>\n";

While the programmer intends to access files such as "/users/cwe/profiles/alice" or "/users/cwe/profiles/bob", there is no verification of the incoming user parameter. An attacker could provide a string such as:

(attack code)

../../../etc/passwd

The program would generate a profile pathname like this:

(result)

/users/cwe/profiles/../../../etc/passwd

When the file is opened, the operating system resolves the "../" during path canonicalization and actually accesses this file:

(result)

/etc/passwd

As a result, the attacker could read the entire text of the password file.

Notice how this code also contains an error message information leak (CWE-209) if the user parameter does not produce a file that exists: the full pathname is provided. Because of the lack of output encoding of the file that is retrieved, there might also be a cross-site scripting problem (CWE-79) if profile contains any HTML, but other code would need to be examined.

Example 2

In the example below, the path to a dictionary file is read from a system property and used to initialize a File object.

(bad code)

Example Language: Java

String filename = System.getProperty("com.domain.application.dictionaryFile");
File dictionaryFile = new File(filename);

However, the path is not validated or modified to prevent it from containing relative or absolute path sequences before creating the File object. This allows anyone who can control the system property to determine what file is used. Ideally, the path should be resolved relative to some kind of application or user home directory.

Example 3

The following code takes untrusted input and uses a regular expression to filter "../" from the input. It then appends this result to the /home/user/ directory and attempts to read the file in the final resulting path.

(bad code)

Example Language: Perl

my $Username = GetUntrustedInput();
$Username =~ s/\.\.\///;
my $filename = "/home/user/" . $Username;
ReadAndSendFile($filename);

Since the regular expression does not have the /g global match modifier, it only removes the first instance of "../" it comes across. So an input value such as:

(attack code)

../../../etc/passwd

will have the first "../" stripped, resulting in:

(result)

../../etc/passwd

This value is then concatenated with the /home/user/ directory:

(result)

/home/user/../../etc/passwd

which causes the /etc/passwd file to be retrieved once the operating system has resolved the ../ sequences in the pathname. This leads to relative path traversal (CWE-23).

Example 4

The following code attempts to validate a given input path by checking it against an allowlist and once validated delete the given file. In this specific case, the path is considered valid if it starts with the string "/safe_dir/".

(bad code)

Example Language: Java

String path = getInputPath();
if (path.startsWith("/safe_dir/"))
{

File f = new File(path);
f.delete()

}

An attacker could provide an input such as this:

(attack code)

/safe_dir/../important.dat

The software assumes that the path is valid because it starts with the "/safe_path/" sequence, but the "../" sequence will cause the program to delete the important.dat file in the parent directory

Example 5

The following code demonstrates the unrestricted upload of a file with a Java servlet and a path traversal vulnerability. The action attribute of an HTML form is sending the upload file request to the Java servlet.

(good code)

Example Language: HTML

<form action="FileUploadServlet" method="post" enctype="multipart/form-data">

Choose a file to upload:
<input type="file" name="filename"/>
<br/>
<input type="submit" name="submit" value="Submit"/>

</form>

When submitted the Java servlet's doPost method will receive the request, extract the name of the file from the Http request header, read the file contents from the request and output the file to the local upload directory.

(bad code)

Example Language: Java

public class FileUploadServlet extends HttpServlet {

...

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

response.setContentType("text/html");
PrintWriter out = response.getWriter();
String contentType = request.getContentType();

// the starting position of the boundary header
int ind = contentType.indexOf("boundary=");
String boundary = contentType.substring(ind+9);

String pLine = new String();
String uploadLocation = new String(UPLOAD_DIRECTORY_STRING); //Constant value

// verify that content type is multipart form data
if (contentType != null && contentType.indexOf("multipart/form-data") != -1) {

// extract the filename from the Http header
BufferedReader br = new BufferedReader(new InputStreamReader(request.getInputStream()));
...
pLine = br.readLine();
String filename = pLine.substring(pLine.lastIndexOf("\\"), pLine.lastIndexOf("\""));
...

// output the file to the local upload directory
try {

BufferedWriter bw = new BufferedWriter(new FileWriter(uploadLocation+filename, true));
for (String line; (line=br.readLine())!=null; ) {

if (line.indexOf(boundary) == -1) {

bw.write(line);
bw.newLine();
bw.flush();

}

} //end of for loop
bw.close();

} catch (IOException ex) {...}
// output successful upload response HTML page

}
// output unsuccessful upload response HTML page
else
{...}

}

...

}

This code does not perform a check on the type of the file being uploaded (CWE-434). This could allow an attacker to upload any executable file or other file with malicious code.

Additionally, the creation of the BufferedWriter object is subject to relative path traversal (CWE-23). Since the code does not check the filename that is provided in the header, an attacker can use "../" sequences to write to files outside of the intended directory. Depending on the executing environment, the attacker may be able to specify arbitrary files to write to, leading to a wide variety of consequences, from code execution, XSS (CWE-79), or system crash.

Example 6

This script intends to read a user-supplied file from the current directory. The user inputs the relative path to the file and the script uses Python's os.path.join() function to combine the path to the current working directory with the provided path to the specified file. This results in an absolute path to the desired file. If the file does not exist when the script attempts to read it, an error is printed to the user.

(bad code)

Example Language: Python

import os
import sys
def main():

filename = sys.argv[1]
path = os.path.join(os.getcwd(), filename)
try:

with open(path, 'r') as f:

file_data = f.read()

except FileNotFoundError as e:

print("Error - file not found")

main()

However, if the user supplies an absolute path, the os.path.join() function will discard the path to the current working directory and use only the absolute path provided. For example, if the current working directory is /home/user/documents, but the user inputs /etc/passwd, os.path.join() will use only /etc/passwd, as it is considered an absolute path. In the above scenario, this would cause the script to access and read the /etc/passwd file.

(good code)

Example Language: Python

import os
import sys
def main():

filename = sys.argv[1]
path = os.path.normpath(f"{os.getcwd()}{os.sep}{filename}")
if path.startswith("/home/cwe/documents/"):

try:

with open(path, 'r') as f:

file_data = f.read()

except FileNotFoundError as e:

print("Error - file not found")

main()

The constructed path string uses os.sep to add the appropriate separation character for the given operating system (e.g. '\' or '/') and the call to os.path.normpath() removes any additional slashes that may have been entered - this may occur particularly when using a Windows path. The path is checked against an expected directory (/home/cwe/documents); otherwise, an attacker could provide relative path sequences like ".." to cause normpath() to generate paths that are outside the intended directory (CWE-23). By putting the pieces of the path string together in this fashion, the script avoids a call to os.path.join() and any potential issues that might arise if an absolute path is entered. With this version of the script, if the current working directory is /home/cwe/documents, and the user inputs /etc/passwd, the resulting path will be /home/cwe/documents/etc/passwd. The user is therefore contained within the current working directory as intended.

Selected Observed Examples

Reference	Description
CVE-2024-37032	Large language model (LLM) management tool does not validate the format of a digest value (CWE-1287) from a private, untrusted model registry, enabling relative path traversal (CWE-23), a.k.a. Probllama
CVE-2024-4315	Chain: API for text generation using Large Language Models (LLMs) does not include the "\" Windows folder separator in its denylist (CWE-184) when attempting to prevent Local File Inclusion via path traversal (CWE-22), allowing deletion of arbitrary files on Windows systems.
CVE-2022-45918	Chain: a learning management tool debugger uses external input to locate previous session logs (CWE-73) and does not properly validate the given path (CWE-20), allowing for filesystem path traversal using "../" sequences (CWE-24)
CVE-2019-20916	Python package manager does not correctly restrict the filename specified in a Content-Disposition header, allowing arbitrary file read using path traversal sequences such as "../"
CVE-2022-31503	Python package constructs filenames using an unsafe os.path.join call on untrusted input, allowing absolute path traversal because os.path.join resets the pathname to an absolute path that is specified as part of the input.
CVE-2022-24877	directory traversal in Go-based Kubernetes operator app allows accessing data from the controller's pod file system via ../ sequences in a yaml file
CVE-2021-21972	Chain: Cloud computing virtualization platform does not require authentication for upload of a tar format file (CWE-306), then uses .. path traversal sequences (CWE-23) in the file to access unexpected files, as exploited in the wild per CISA KEV.
CVE-2020-4053	a Kubernetes package manager written in Go allows malicious plugins to inject path traversal sequences into a plugin archive ("Zip slip") to copy a file outside the intended directory
CVE-2020-3452	Chain: security product has improper input validation (CWE-20) leading to directory traversal (CWE-22), as exploited in the wild per CISA KEV.
CVE-2019-10743	Go-based archive library allows extraction of files to locations outside of the target folder with "../" path traversal sequences in filenames in a zip file, aka "Zip Slip"
CVE-2010-0467	Newsletter module allows reading arbitrary files using "../" sequences.
CVE-2006-7079	Chain: PHP app uses extract for register_globals compatibility layer (CWE-621), enabling path traversal (CWE-22)
CVE-2009-4194	FTP server allows deletion of arbitrary files using ".." in the DELE command.
CVE-2009-4053	FTP server allows creation of arbitrary directories using ".." in the MKD command.
CVE-2009-0244	FTP service for a Bluetooth device allows listing of directories, and creation or reading of files using ".." sequences.
CVE-2009-4013	Software package maintenance program allows overwriting arbitrary files using "../" sequences.
CVE-2009-4449	Bulletin board allows attackers to determine the existence of files using the avatar.
CVE-2009-4581	PHP program allows arbitrary code execution using ".." in filenames that are fed to the include() function.
CVE-2010-0012	Overwrite of files using a .. in a Torrent file.
CVE-2010-0013	Chat program allows overwriting files using a custom smiley request.
CVE-2008-5748	Chain: external control of values for user's desired language and theme enables path traversal.
CVE-2009-1936	Chain: library file sends a redirect if it is directly requested but continues to execute, allowing remote file inclusion and path traversal.

Weakness Ordinalities

Ordinality	Description
Primary	(where the weakness exists independent of other weaknesses)
Resultant	(where the weakness is typically related to the presence of some other weaknesses)

Detection Methods

Method	Details
Automated Static Analysis	Automated techniques can find areas where path traversal weaknesses exist. However, tuning or customization may be required to remove or de-prioritize path-traversal problems that are only exploitable by the product's administrator - or other privileged users - and thus potentially valid behavior or, at worst, a bug instead of a vulnerability. Effectiveness: High
Manual Static Analysis	Manual white box techniques may be able to provide sufficient code coverage and reduction of false positives if all file access operations can be assessed within limited time constraints. Effectiveness: High
Automated Static Analysis - Binary or Bytecode	According to SOAR, the following detection techniques may be useful: Highly cost effective: Bytecode Weakness Analysis - including disassembler + source code weakness analysis Cost effective for partial coverage: Binary Weakness Analysis - including disassembler + source code weakness analysis Effectiveness: High
Manual Static Analysis - Binary or Bytecode	According to SOAR, the following detection techniques may be useful: Cost effective for partial coverage: Binary / Bytecode disassembler - then use manual analysis for vulnerabilities & anomalies Effectiveness: SOAR Partial
Dynamic Analysis with Automated Results Interpretation	According to SOAR, the following detection techniques may be useful: Highly cost effective: Web Application Scanner Web Services Scanner Database Scanners Effectiveness: High
Dynamic Analysis with Manual Results Interpretation	According to SOAR, the following detection techniques may be useful: Highly cost effective: Fuzz Tester Framework-based Fuzzer Effectiveness: High
Manual Static Analysis - Source Code	According to SOAR, the following detection techniques may be useful: Highly cost effective: Manual Source Code Review (not inspections) Cost effective for partial coverage: Focused Manual Spotcheck - Focused manual analysis of source Effectiveness: High
Automated Static Analysis - Source Code	According to SOAR, the following detection techniques may be useful: Highly cost effective: Source code Weakness Analyzer Context-configured Source Code Weakness Analyzer Effectiveness: High
Architecture or Design Review	According to SOAR, the following detection techniques may be useful: Highly cost effective: Formal Methods / Correct-By-Construction Cost effective for partial coverage: Inspection (IEEE 1028 standard) (can apply to requirements, design, source code, etc.) Effectiveness: High

Functional Areas

File Processing

Affected Resources

File or Directory

Memberships

Nature	Type	ID	Name
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	635	Weaknesses Originally Used by NVD from 2008 to 2016
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	715	OWASP Top Ten 2007 Category A4 - Insecure Direct Object Reference
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	723	OWASP Top Ten 2004 Category A2 - Broken Access Control
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	743	CERT C Secure Coding Standard (2008) Chapter 10 - Input Output (FIO)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	802	2010 Top 25 - Risky Resource Management
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	813	OWASP Top Ten 2010 Category A4 - Insecure Direct Object References
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	865	2011 Top 25 - Risky Resource Management
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	877	CERT C++ Secure Coding Section 09 - Input Output (FIO)
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	884	CWE Cross-section
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	932	OWASP Top Ten 2013 Category A4 - Insecure Direct Object References
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	981	SFP Secondary Cluster: Path Traversal
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1031	OWASP Top Ten 2017 Category A5 - Broken Access Control
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1131	CISQ Quality Measures (2016) - Security
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1179	SEI CERT Perl Coding Standard - Guidelines 01. Input Validation and Data Sanitization (IDS)
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1200	Weaknesses in the 2019 CWE Top 25 Most Dangerous Software Errors
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1308	CISQ Quality Measures - Security
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1337	Weaknesses in the 2021 CWE Top 25 Most Dangerous Software Weaknesses
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1340	CISQ Data Protection Measures
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1345	OWASP Top Ten 2021 Category A01:2021 - Broken Access Control
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1350	Weaknesses in the 2020 CWE Top 25 Most Dangerous Software Weaknesses
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1387	Weaknesses in the 2022 CWE Top 25 Most Dangerous Software Weaknesses
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1404	Comprehensive Categorization: File Handling
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1425	Weaknesses in the 2023 CWE Top 25 Most Dangerous Software Weaknesses
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1430	Weaknesses in the 2024 CWE Top 25 Most Dangerous Software Weaknesses

Vulnerability Mapping Notes

Usage	ALLOWED (this CWE ID may be used to map to real-world vulnerabilities)
Reason	Acceptable-Use
Rationale	This CWE entry is at the Base level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.
Comments	Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction.

Notes

Relationship

Pathname equivalence can be regarded as a type of canonicalization error.

Relationship

Some pathname equivalence issues are not directly related to directory traversal, rather are used to bypass security-relevant checks for whether a file/directory can be accessed by the attacker (e.g. a trailing "/" on a filename could bypass access rules that don't expect a trailing /, causing a server to provide the file when it normally would not).

Terminology

Like other weaknesses, terminology is often based on the types of manipulations used, instead of the underlying weaknesses. Some people use "directory traversal" only to refer to the injection of ".." and equivalent sequences whose specific meaning is to traverse directories.

Other variants like "absolute pathname" and "drive letter" have the *effect* of directory traversal, but some people may not call it such, since it doesn't involve ".." or equivalent.

Research Gap

Many variants of path traversal attacks are probably under-studied with respect to root cause. CWE-790 and CWE-182 begin to cover part of this gap.

Research Gap

Incomplete diagnosis or reporting of vulnerabilities can make it difficult to know which variant is affected. For example, a researcher might say that "..\" is vulnerable, but not test "../" which may also be vulnerable.

Any combination of directory separators ("/", "\", etc.) and numbers of "." (e.g. "....") can produce unique variants; for example, the "//../" variant is not listed (CVE-2004-0325). See this entry's children and lower-level descendants.

Other

In many programming languages, the injection of a null byte (the 0 or NUL) may allow an attacker to truncate a generated filename to apply to a wider range of files. For example, the product may add ".txt" to any pathname, thus limiting the attacker to text files, but a null injection may effectively remove this restriction.

Taxonomy Mappings

Mapped Taxonomy Name	Node ID	Fit	Mapped Node Name
PLOVER			Path Traversal
OWASP Top Ten 2007	A4	CWE More Specific	Insecure Direct Object Reference
OWASP Top Ten 2004	A2	CWE More Specific	Broken Access Control
CERT C Secure Coding	FIO02-C		Canonicalize path names originating from untrusted sources
SEI CERT Perl Coding Standard	IDS00-PL	Exact	Canonicalize path names before validating them
WASC	33		Path Traversal
Software Fault Patterns	SFP16		Path Traversal
OMG ASCSM	ASCSM-CWE-22

Related Attack Patterns

CAPEC-ID	Attack Pattern Name
CAPEC-126	Path Traversal
CAPEC-64	Using Slashes and URL Encoding Combined to Bypass Validation Logic
CAPEC-76	Manipulating Web Input to File System Calls
CAPEC-78	Using Escaped Slashes in Alternate Encoding
CAPEC-79	Using Slashes in Alternate Encoding

References

[REF-7]	Michael Howard and David LeBlanc. "Writing Secure Code". Chapter 11, "Directory Traversal and Using Parent Paths (..)" Page 370. 2nd Edition. Microsoft Press. 2002-12-04. <https://www.microsoftpressstore.com/store/writing-secure-code-9780735617223>.
[REF-45]	OWASP. "OWASP Enterprise Security API (ESAPI) Project". <http://www.owasp.org/index.php/ESAPI>.
[REF-185]	OWASP. "Testing for Path Traversal (OWASP-AZ-001)". <http://www.owasp.org/index.php/Testing_for_Path_Traversal_(OWASP-AZ-001)>.
[REF-186]	Johannes Ullrich. "Top 25 Series - Rank 7 - Path Traversal". SANS Software Security Institute. 2010-03-09. <https://www.sans.org/blog/top-25-series-rank-7-path-traversal/>. (URL validated: 2023-04-07)
[REF-76]	Sean Barnum and Michael Gegick. "Least Privilege". 2005-09-14. <https://web.archive.org/web/20211209014121/https://www.cisa.gov/uscert/bsi/articles/knowledge/principles/least-privilege>. (URL validated: 2023-04-07)
[REF-62]	Mark Dowd, John McDonald and Justin Schuh. "The Art of Software Security Assessment". Chapter 9, "Filenames and Paths", Page 503. 1st Edition. Addison Wesley. 2006.
[REF-962]	Object Management Group (OMG). "Automated Source Code Security Measure (ASCSM)". ASCSM-CWE-22. 2016-01. <http://www.omg.org/spec/ASCSM/1.0/>.
[REF-1448]	Cybersecurity and Infrastructure Security Agency. "Secure by Design Alert: Eliminating Directory Traversal Vulnerabilities in Software". 2024-05-02. <https://www.cisa.gov/resources-tools/resources/secure-design-alert-eliminating-directory-traversal-vulnerabilities-software>. (URL validated: 2024-07-14)

Content History

Submissions
Submission Date	Submitter	Organization
2006-07-19 (CWE Draft 3, 2006-07-19)	PLOVER
2006-07-19 (CWE Draft 3, 2006-07-19)
Contributions
Contribution Date	Contributor	Organization
2022-07-11	Nick Johnston
2022-07-11	Identified weakness in Perl demonstrative example
2024-02-29 (CWE 4.15, 2024-07-16)	Abhi Balakrishnan
2024-02-29 (CWE 4.15, 2024-07-16)	Provided diagram to improve CWE usability
2024-11-01	Drew Buttner	MITRE
2024-11-01	Identified weakness in "good code" for Python demonstrative example
Modifications
Modification Date	Modifier	Organization
2025-04-03 (CWE 4.17, 2025-04-03)	CWE Content Team	MITRE
2025-04-03 (CWE 4.17, 2025-04-03)	updated Relationships
2024-11-19 (CWE 4.16, 2024-11-19)	CWE Content Team	MITRE
2024-11-19 (CWE 4.16, 2024-11-19)	updated Demonstrative_Examples, Relationships
2024-07-16 (CWE 4.15, 2024-07-16)	CWE Content Team	MITRE
2024-07-16 (CWE 4.15, 2024-07-16)	updated Common_Consequences, Description, Diagram, Observed_Examples, Other_Notes, References
2023-10-26	CWE Content Team	MITRE
2023-10-26	updated Observed_Examples
2023-06-29	CWE Content Team	MITRE
2023-06-29	updated Mapping_Notes, Relationships
2023-04-27	CWE Content Team	MITRE
2023-04-27	updated Demonstrative_Examples, References, Relationships, Time_of_Introduction
2023-01-31	CWE Content Team	MITRE
2023-01-31	updated Common_Consequences, Description, Detection_Factors
2022-10-13	CWE Content Team	MITRE
2022-10-13	updated Observed_Examples, References
2022-06-28	CWE Content Team	MITRE
2022-06-28	updated Observed_Examples, Relationships
2021-10-28	CWE Content Team	MITRE
2021-10-28	updated Observed_Examples, Relationships
2021-07-20	CWE Content Team	MITRE
2021-07-20	updated Relationships
2021-03-15	CWE Content Team	MITRE
2021-03-15	updated Demonstrative_Examples, Relationships
2020-12-10	CWE Content Team	MITRE
2020-12-10	updated Potential_Mitigations, Relationships
2020-08-20	CWE Content Team	MITRE
2020-08-20	updated Relationships
2020-06-25	CWE Content Team	MITRE
2020-06-25	updated Demonstrative_Examples, Potential_Mitigations
2020-02-24	CWE Content Team	MITRE
2020-02-24	updated Potential_Mitigations, Relationships
2019-09-19	CWE Content Team	MITRE
2019-09-19	updated Relationships
2019-06-20	CWE Content Team	MITRE
2019-06-20	updated Related_Attack_Patterns, Relationships, Type
2019-01-03	CWE Content Team	MITRE
2019-01-03	updated References, Related_Attack_Patterns, Relationships, Taxonomy_Mappings
2018-03-27	CWE Content Team	MITRE
2018-03-27	updated References, Relationships
2017-11-08	CWE Content Team	MITRE
2017-11-08	updated Affected_Resources, Causal_Nature, Likelihood_of_Exploit, References, Relationships, Relevant_Properties, Taxonomy_Mappings
2017-05-03	CWE Content Team	MITRE
2017-05-03	updated Demonstrative_Examples
2017-01-19	CWE Content Team	MITRE
2017-01-19	updated Related_Attack_Patterns
2015-12-07	CWE Content Team	MITRE
2015-12-07	updated Relationships
2014-07-30	CWE Content Team	MITRE
2014-07-30	updated Detection_Factors, Relationships, Taxonomy_Mappings
2014-06-23	CWE Content Team	MITRE
2014-06-23	updated Other_Notes, Research_Gaps
2013-07-17	CWE Content Team	MITRE
2013-07-17	updated Related_Attack_Patterns, Relationships
2013-02-21	CWE Content Team	MITRE
2013-02-21	updated Observed_Examples
2012-10-30	CWE Content Team	MITRE
2012-10-30	updated Potential_Mitigations
2012-05-11	CWE Content Team	MITRE
2012-05-11	updated Demonstrative_Examples, References, Relationships
2011-09-13	CWE Content Team	MITRE
2011-09-13	updated Potential_Mitigations, References, Relationships, Taxonomy_Mappings
2011-06-27	CWE Content Team	MITRE
2011-06-27	updated Relationships
2011-03-29	CWE Content Team	MITRE
2011-03-29	updated Potential_Mitigations
2010-12-13	CWE Content Team	MITRE
2010-12-13	updated Potential_Mitigations
2010-09-27	CWE Content Team	MITRE
2010-09-27	updated Potential_Mitigations
2010-06-21	CWE Content Team	MITRE
2010-06-21	updated Common_Consequences, Demonstrative_Examples, Description, Detection_Factors, Potential_Mitigations, References, Relationships
2010-02-16	CWE Content Team	MITRE
2010-02-16	updated Alternate_Terms, Applicable_Platforms, Common_Consequences, Demonstrative_Examples, Description, Detection_Factors, Likelihood_of_Exploit, Name, Observed_Examples, Other_Notes, Potential_Mitigations, References, Related_Attack_Patterns, Relationship_Notes, Relationships, Research_Gaps, Taxonomy_Mappings, Terminology_Notes, Time_of_Introduction, Weakness_Ordinalities
2009-07-27	CWE Content Team	MITRE
2009-07-27	updated Potential_Mitigations
2008-11-24	CWE Content Team	MITRE
2008-11-24	updated Relationships, Taxonomy_Mappings
2008-10-14	CWE Content Team	MITRE
2008-10-14	updated Description
2008-09-08	CWE Content Team	MITRE
2008-09-08	updated Alternate_Terms, Relationships, Other_Notes, Relationship_Notes, Relevant_Properties, Taxonomy_Mappings, Weakness_Ordinalities
2008-08-15		Veracode
2008-08-15	Suggested OWASP Top Ten 2004 mapping
2008-07-01	Eric Dalci	Cigital
2008-07-01	updated Potential_Mitigations, Time_of_Introduction
Previous Entry Names
Change Date	Previous Entry Name
2010-02-16	Path Traversal

Weakness ID: 59

View customized information:

Description

The product attempts to access a file based on the filename, but it does not properly prevent that filename from identifying a link or shortcut that resolves to an unintended resource.

Alternate Terms

insecure temporary file	Some people use the phrase "insecure temporary file" when referring to a link following weakness, but other weaknesses can produce insecure temporary files without any symlink involvement at all.
Zip Slip	"Zip slip" is an attack that uses file archives (e.g., ZIP, tar, rar, etc.) that contain filenames with path traversal sequences that cause the files to be written outside of the directory under which the archive is expected to be extracted [REF-1282]. It is most commonly used for relative path traversal (CWE-23) and link following (CWE-59).

Common Consequences

Impact	Details
Read Files or Directories; Modify Files or Directories; Bypass Protection Mechanism	Scope: Confidentiality, Integrity, Access Control An attacker may be able to traverse the file system to unintended locations and read or overwrite the contents of unexpected files. If the files are used for a security mechanism then an attacker may be able to bypass the mechanism.
Execute Unauthorized Code or Commands	Scope: Other Windows simple shortcuts, sometimes referred to as soft links, can be exploited remotely since a ".LNK" file can be uploaded like a normal file. This can enable remote execution.

Potential Mitigations

Phase(s)	Mitigation
Architecture and Design	Strategy: Separation of Privilege Follow the principle of least privilege when assigning access rights to entities in a software system. Denying access to a file can prevent an attacker from replacing that file with a link to a sensitive file. Ensure good compartmentalization in the system to provide protected areas that can be trusted.

Relationships

Relevant to the view "Research Concepts" (View-1000)

Nature	Type	ID	Name
ChildOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	706	Use of Incorrectly-Resolved Name or Reference
ParentOf	Composite - a Compound Element that consists of two or more distinct weaknesses, in which all weaknesses must be present at the same time in order for a potential vulnerability to arise. Removing any of the weaknesses eliminates or sharply reduces the risk. One weakness, X, can be "broken down" into component weaknesses Y and Z. There can be cases in which one weakness might not be essential to a composite, but changes the nature of the composite when it becomes a vulnerability.	61	UNIX Symbolic Link (Symlink) Following
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	62	UNIX Hard Link
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	64	Windows Shortcut Following (.LNK)
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	65	Windows Hard Link
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	1386	Insecure Operation on Windows Junction / Mount Point
CanFollow	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	73	External Control of File Name or Path
CanFollow	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	363	Race Condition Enabling Link Following

Relevant to the view "Software Development" (View-699)

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1219	File Handling Issues

Relevant to the view "Weaknesses for Simplified Mapping of Published Vulnerabilities" (View-1003)

Nature	Type	ID	Name
ChildOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	706	Use of Incorrectly-Resolved Name or Reference

Relevant to the view "Architectural Concepts" (View-1008)

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1019	Validate Inputs

Background Details

Soft links are a UNIX term that is synonymous with simple shortcuts on Windows-based platforms.

Modes Of Introduction

Phase	Note
Implementation	REALIZATION: This weakness is caused during implementation of an architectural security tactic.

Applicable Platforms

Languages	Class: Not Language-Specific (Undetermined Prevalence)
Operating Systems	Class: Windows (Sometimes Prevalent) Class: Unix (Often Prevalent)

Likelihood Of Exploit

Medium

Selected Observed Examples

Reference	Description
CVE-1999-1386	Some versions of Perl follow symbolic links when running with the -e option, which allows local users to overwrite arbitrary files via a symlink attack.
CVE-2000-1178	Text editor follows symbolic links when creating a rescue copy during an abnormal exit, which allows local users to overwrite the files of other users.
CVE-2004-0217	Antivirus update allows local users to create or append to arbitrary files via a symlink attack on a logfile.
CVE-2003-0517	Symlink attack allows local users to overwrite files.
CVE-2004-0689	Window manager does not properly handle when certain symbolic links point to "stale" locations, which could allow local users to create or truncate arbitrary files.
CVE-2005-1879	Second-order symlink vulnerabilities
CVE-2005-1880	Second-order symlink vulnerabilities
CVE-2005-1916	Symlink in Python program
CVE-2000-0972	Setuid product allows file reading by replacing a file being edited with a symlink to the targeted file, leaking the result in error messages when parsing fails.
CVE-2005-0824	Signal causes a dump that follows symlinks.
CVE-2001-1494	Hard link attack, file overwrite; interesting because program checks against soft links
CVE-2002-0793	Hard link and possibly symbolic link following vulnerabilities in embedded operating system allow local users to overwrite arbitrary files.
CVE-2003-0578	Server creates hard links and unlinks files as root, which allows local users to gain privileges by deleting and overwriting arbitrary files.
CVE-1999-0783	Operating system allows local users to conduct a denial of service by creating a hard link from a device special file to a file on an NFS file system.
CVE-2004-1603	Web hosting manager follows hard links, which allows local users to read or modify arbitrary files.
CVE-2004-1901	Package listing system allows local users to overwrite arbitrary files via a hard link attack on the lockfiles.
CVE-2005-1111	Hard link race condition
CVE-2000-0342	Mail client allows remote attackers to bypass the user warning for executable attachments such as .exe, .com, and .bat by using a .lnk file that refers to the attachment, aka "Stealth Attachment."
CVE-2001-1042	FTP server allows remote attackers to read arbitrary files and directories by uploading a .lnk (link) file that points to the target file.
CVE-2001-1043	FTP server allows remote attackers to read arbitrary files and directories by uploading a .lnk (link) file that points to the target file.
CVE-2005-0587	Browser allows remote malicious web sites to overwrite arbitrary files by tricking the user into downloading a .LNK (link) file twice, which overwrites the file that was referenced in the first .LNK file.
CVE-2001-1386	".LNK." - .LNK with trailing dot
CVE-2003-1233	Rootkits can bypass file access restrictions to Windows kernel directories using NtCreateSymbolicLinkObject function to create symbolic link
CVE-2002-0725	File system allows local attackers to hide file usage activities via a hard link to the target file, which causes the link to be recorded in the audit trail instead of the target file.
CVE-2003-0844	Web server plugin allows local users to overwrite arbitrary files via a symlink attack on predictable temporary filenames.
CVE-2015-3629	A Libcontainer used in Docker Engine allows local users to escape containerization and write to an arbitrary file on the host system via a symlink attack in an image when respawning a container.
CVE-2021-21272	"Zip Slip" vulnerability in Go-based Open Container Initiative (OCI) registries product allows writing arbitrary files outside intended directory via symbolic links or hard links in a gzipped tarball.
CVE-2020-27833	"Zip Slip" vulnerability in container management product allows writing arbitrary files outside intended directory via a container image (.tar format) with filenames that are symbolic links that point to other files within the same tar file; however, the files being pointed to can also be symbolic links to destinations outside the intended directory, bypassing the initial check.

Weakness Ordinalities

Ordinality	Description
Resultant	(where the weakness is typically related to the presence of some other weaknesses)

Detection Methods

Method	Details
Automated Static Analysis - Binary or Bytecode	According to SOAR, the following detection techniques may be useful: Cost effective for partial coverage: Bytecode Weakness Analysis - including disassembler + source code weakness analysis Effectiveness: SOAR Partial
Manual Static Analysis - Binary or Bytecode	According to SOAR, the following detection techniques may be useful: Cost effective for partial coverage: Binary / Bytecode disassembler - then use manual analysis for vulnerabilities & anomalies Effectiveness: SOAR Partial
Dynamic Analysis with Automated Results Interpretation	According to SOAR, the following detection techniques may be useful: Cost effective for partial coverage: Web Application Scanner Web Services Scanner Database Scanners Effectiveness: SOAR Partial
Dynamic Analysis with Manual Results Interpretation	According to SOAR, the following detection techniques may be useful: Cost effective for partial coverage: Fuzz Tester Framework-based Fuzzer Effectiveness: SOAR Partial
Manual Static Analysis - Source Code	According to SOAR, the following detection techniques may be useful: Highly cost effective: Focused Manual Spotcheck - Focused manual analysis of source Manual Source Code Review (not inspections) Effectiveness: High
Automated Static Analysis - Source Code	According to SOAR, the following detection techniques may be useful: Cost effective for partial coverage: Source code Weakness Analyzer Context-configured Source Code Weakness Analyzer Effectiveness: SOAR Partial
Architecture or Design Review	According to SOAR, the following detection techniques may be useful: Highly cost effective: Formal Methods / Correct-By-Construction Cost effective for partial coverage: Inspection (IEEE 1028 standard) (can apply to requirements, design, source code, etc.) Effectiveness: High

Functional Areas

File Processing

Affected Resources

File or Directory

Memberships

Nature	Type	ID	Name
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	635	Weaknesses Originally Used by NVD from 2008 to 2016
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	743	CERT C Secure Coding Standard (2008) Chapter 10 - Input Output (FIO)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	748	CERT C Secure Coding Standard (2008) Appendix - POSIX (POS)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	808	2010 Top 25 - Weaknesses On the Cusp
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	877	CERT C++ Secure Coding Section 09 - Input Output (FIO)
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	884	CWE Cross-section
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	980	SFP Secondary Cluster: Link in Resource Name Resolution
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1185	SEI CERT Perl Coding Standard - Guidelines 07. File Input and Output (FIO)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1345	OWASP Top Ten 2021 Category A01:2021 - Broken Access Control
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1404	Comprehensive Categorization: File Handling

Vulnerability Mapping Notes

Usage	ALLOWED (this CWE ID may be used to map to real-world vulnerabilities)
Reason	Acceptable-Use
Rationale	This CWE entry is at the Base level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.
Comments	Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction.

Notes

Theoretical

Link following vulnerabilities are Multi-factor Vulnerabilities (MFV). They are the combination of multiple elements: file or directory permissions, filename predictability, race conditions, and in some cases, a design limitation in which there is no mechanism for performing atomic file creation operations.

Some potential factors are race conditions, permissions, and predictability.

Taxonomy Mappings

Mapped Taxonomy Name	Node ID	Fit	Mapped Node Name
PLOVER			Link Following
CERT C Secure Coding	FIO02-C		Canonicalize path names originating from untrusted sources
CERT C Secure Coding	POS01-C		Check for the existence of links when dealing with files
SEI CERT Perl Coding Standard	FIO01-PL	CWE More Specific	Do not operate on files that can be modified by untrusted users
Software Fault Patterns	SFP18		Link in resource name resolution

Related Attack Patterns

CAPEC-ID	Attack Pattern Name
CAPEC-132	Symlink Attack
CAPEC-17	Using Malicious Files
CAPEC-35	Leverage Executable Code in Non-Executable Files
CAPEC-76	Manipulating Web Input to File System Calls

References

[REF-62]	Mark Dowd, John McDonald and Justin Schuh. "The Art of Software Security Assessment". Chapter 9, "Symbolic Link Attacks", Page 518. 1st Edition. Addison Wesley. 2006.
[REF-1282]	Snyk. "Zip Slip Vulnerability". 2018-06-05. <https://security.snyk.io/research/zip-slip-vulnerability>.

Content History

Submissions
Submission Date	Submitter	Organization
2006-07-19 (CWE Draft 3, 2006-07-19)	PLOVER
2006-07-19 (CWE Draft 3, 2006-07-19)
Modifications
Modification Date	Modifier	Organization
2023-06-29	CWE Content Team	MITRE
2023-06-29	updated Mapping_Notes
2023-04-27	CWE Content Team	MITRE
2023-04-27	updated Relationships
2023-01-31	CWE Content Team	MITRE
2023-01-31	updated Description
2022-10-13	CWE Content Team	MITRE
2022-10-13	updated Alternate_Terms, Background_Details, Observed_Examples, References, Relationship_Notes, Theoretical_Notes
2022-06-28	CWE Content Team	MITRE
2022-06-28	updated Relationships
2022-04-28	CWE Content Team	MITRE
2022-04-28	updated Research_Gaps
2021-10-28	CWE Content Team	MITRE
2021-10-28	updated Relationships
2021-03-15	CWE Content Team	MITRE
2021-03-15	updated Relationships
2020-02-24	CWE Content Team	MITRE
2020-02-24	updated Relationships
2019-06-20	CWE Content Team	MITRE
2019-06-20	updated Relationships
2019-01-03	CWE Content Team	MITRE
2019-01-03	updated Taxonomy_Mappings
2017-11-08	CWE Content Team	MITRE
2017-11-08	updated Affected_Resources, Applicable_Platforms, Causal_Nature, Common_Consequences, Functional_Areas, Likelihood_of_Exploit, Modes_of_Introduction, Relationships, Taxonomy_Mappings
2015-12-07	CWE Content Team	MITRE
2015-12-07	updated Relationships
2014-07-30	CWE Content Team	MITRE
2014-07-30	updated Detection_Factors, Relationships, Taxonomy_Mappings
2014-06-23	CWE Content Team	MITRE
2014-06-23	updated Common_Consequences, Other_Notes
2012-10-30	CWE Content Team	MITRE
2012-10-30	updated Potential_Mitigations
2012-05-11	CWE Content Team	MITRE
2012-05-11	updated Common_Consequences, Observed_Examples, References, Relationships
2011-09-13	CWE Content Team	MITRE
2011-09-13	updated Relationships, Taxonomy_Mappings
2011-06-01	CWE Content Team	MITRE
2011-06-01	updated Common_Consequences
2010-04-05	CWE Content Team	MITRE
2010-04-05	updated Related_Attack_Patterns
2010-02-16	CWE Content Team	MITRE
2010-02-16	updated Potential_Mitigations, Relationships
2009-10-29	CWE Content Team	MITRE
2009-10-29	updated Background_Details, Other_Notes
2009-05-27	CWE Content Team	MITRE
2009-05-27	updated Description, Name
2009-01-12	CWE Content Team	MITRE
2009-01-12	updated Relationships
2008-11-24	CWE Content Team	MITRE
2008-11-24	updated Relationships, Taxonomy_Mappings
2008-09-08	CWE Content Team	MITRE
2008-09-08	updated Alternate_Terms, Applicable_Platforms, Relationships, Other_Notes, Relationship_Notes, Taxonomy_Mappings, Weakness_Ordinalities
2008-07-01	Eric Dalci	Cigital
2008-07-01	updated Time_of_Introduction
Previous Entry Names
Change Date	Previous Entry Name
2008-04-11	Link Following
2009-05-27	Failure to Resolve Links Before File Access (aka 'Link Following')

Weakness ID: 88

View customized information:

Description

Extended Description

When creating commands using interpolation into a string, developers may assume that only the arguments/options that they specify will be processed. This assumption may be even stronger when the programmer has encoded the command in a way that prevents separate commands from being provided maliciously, e.g. in the case of shell metacharacters. When constructing the command, the developer may use whitespace or other delimiters that are required to separate arguments when the command. However, if an attacker can provide an untrusted input that contains argument-separating delimiters, then the resulting command will have more arguments than intended by the developer. The attacker may then be able to change the behavior of the command. Depending on the functionality supported by the extraneous arguments, this may have security-relevant consequences.

Common Consequences

Impact	Details
Execute Unauthorized Code or Commands; Alter Execution Logic; Read Application Data; Modify Application Data	Scope: Confidentiality, Integrity, Availability, Other An attacker could include arguments that allow unintended commands or code to be executed, allow sensitive data to be read or modified or could cause other unintended behavior.

Potential Mitigations

Phase(s)	Mitigation
Implementation	Strategy: Parameterization Where possible, avoid building a single string that contains the command and its arguments. Some languages or frameworks have functions that support specifying independent arguments, e.g. as an array, which is used to automatically perform the appropriate quoting or escaping while building the command. For example, in PHP, escapeshellarg() can be used to escape a single argument to system(), or exec() can be called with an array of arguments. In C, code can often be refactored from using system() - which accepts a single string - to using exec(), which requires separate function arguments for each parameter. Effectiveness: High
Architecture and Design	Strategy: Input Validation Understand all the potential areas where untrusted inputs can enter your product: parameters or arguments, cookies, anything read from the network, environment variables, request headers as well as content, URL components, e-mail, files, databases, and any external systems that provide data to the application. Perform input validation at well-defined interfaces.
Implementation	Strategy: Input Validation Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does. When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue." Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.
Implementation	Directly convert your input type into the expected data type, such as using a conversion function that translates a string into a number. After converting to the expected data type, ensure that the input's values fall within the expected range of allowable values and that multi-field consistencies are maintained.
Implementation	Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180, CWE-181). Make sure that your application does not inadvertently decode the same input twice (CWE-174). Such errors could be used to bypass allowlist schemes by introducing dangerous inputs after they have been checked. Use libraries such as the OWASP ESAPI Canonicalization control. Consider performing repeated canonicalization until your input does not change any more. This will avoid double-decoding and similar scenarios, but it might inadvertently modify inputs that are allowed to contain properly-encoded dangerous content.
Implementation	When exchanging data between components, ensure that both components are using the same character encoding. Ensure that the proper encoding is applied at each interface. Explicitly set the encoding you are using whenever the protocol allows you to do so.
Implementation	When your application combines data from multiple sources, perform the validation after the sources have been combined. The individual data elements may pass the validation step but violate the intended restrictions after they have been combined.
Testing	Use automated static analysis tools that target this type of weakness. Many modern techniques use data flow analysis to minimize the number of false positives. This is not a perfect solution, since 100% accuracy and coverage are not feasible.
Testing	Use dynamic tools and techniques that interact with the product using large test suites with many diverse inputs, such as fuzz testing (fuzzing), robustness testing, and fault injection. The product's operation may slow down, but it should not become unstable, crash, or generate incorrect results.

Relationships

Relevant to the view "Research Concepts" (View-1000)

Nature	Type	ID	Name
ChildOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	77	Improper Neutralization of Special Elements used in a Command ('Command Injection')

Relevant to the view "Software Development" (View-699)

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	137	Data Neutralization Issues

Relevant to the view "Weaknesses for Simplified Mapping of Published Vulnerabilities" (View-1003)

Nature	Type	ID	Name
ChildOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	74	Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')

Relevant to the view "Architectural Concepts" (View-1008)

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1019	Validate Inputs

Relevant to the view "CISQ Quality Measures (2020)" (View-1305)

Nature	Type	ID	Name
ChildOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	77	Improper Neutralization of Special Elements used in a Command ('Command Injection')

Relevant to the view "CISQ Data Protection Measures" (View-1340)

Nature	Type	ID	Name
ChildOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	77	Improper Neutralization of Special Elements used in a Command ('Command Injection')

Modes Of Introduction

Phase	Note
Implementation	REALIZATION: This weakness is caused during implementation of an architectural security tactic.

Applicable Platforms

Languages

Class: Not Language-Specific (Undetermined Prevalence)

PHP (Often Prevalent)

Demonstrative Examples

Example 1

Consider the following program. It intends to perform an "ls -l" on an input filename. The validate_name() subroutine performs validation on the input to make sure that only alphanumeric and "-" characters are allowed, which avoids path traversal (CWE-22) and OS command injection (CWE-78) weaknesses. Only filenames like "abc" or "d-e-f" are intended to be allowed.

(bad code)

Example Language: Perl

my $arg = GetArgument("filename");
do_listing($arg);

sub do_listing {

my($fname) = @_;
if (! validate_name($fname)) {

print "Error: name is not well-formed!\n";
return;

}
# build command
my $cmd = "/bin/ls -l $fname";
system($cmd);

}

sub validate_name {

my($name) = @_;
if ($name =~ /^[\w\-]+$/) {

return(1);

}
else {

return(0);

}

However, validate_name() allows filenames that begin with a "-". An adversary could supply a filename like "-aR", producing the "ls -l -aR" command (CWE-88), thereby getting a full recursive listing of the entire directory and all of its sub-directories.

There are a couple possible mitigations for this weakness. One would be to refactor the code to avoid using system() altogether, instead relying on internal functions.

Another option could be to add a "--" argument to the ls command, such as "ls -l --", so that any remaining arguments are treated as filenames, causing any leading "-" to be treated as part of a filename instead of another option.

Another fix might be to change the regular expression used in validate_name to force the first character of the filename to be a letter or number, such as:

(good code)

Example Language: Perl

if ($name =~ /^\w[\w\-]+$/) ...

Example 2

CVE-2016-10033 / [REF-1249] provides a useful real-world example of this weakness within PHPMailer.

The program calls PHP's mail() function to compose and send mail. The fifth argument to mail() is a set of parameters. The program intends to provide a "-fSENDER" parameter, where SENDER is expected to be a well-formed email address. The program has already validated the e-mail address before invoking mail(), but there is a lot of flexibility in what constitutes a well-formed email address, including whitespace. With some additional allowed characters to perform some escaping, the adversary can specify an additional "-o" argument (listing an output file) and a "-X" argument (giving a program to execute). Additional details for this kind of exploit are in [REF-1250].

Selected Observed Examples

Reference	Description
CVE-2022-36069	Python-based dependency management tool avoids OS command injection when generating Git commands but allows injection of optional arguments with input beginning with a dash (CWE-88), potentially allowing for code execution.
CVE-1999-0113	Canonical Example - "-froot" argument is passed on to another program, where the "-f" causes execution as user "root"
CVE-2001-0150	Web browser executes Telnet sessions using command line arguments that are specified by the web site, which could allow remote attackers to execute arbitrary commands.
CVE-2001-0667	Web browser allows remote attackers to execute commands by spawning Telnet with a log file option on the command line and writing arbitrary code into an executable file which is later executed.
CVE-2002-0985	Argument injection vulnerability in the mail function for PHP may allow attackers to bypass safe mode restrictions and modify command line arguments to the MTA (e.g. sendmail) possibly executing commands.
CVE-2003-0907	Help and Support center in windows does not properly validate HCP URLs, which allows remote attackers to execute arbitrary code via quotation marks in an "hcp://" URL.
CVE-2004-0121	Mail client does not sufficiently filter parameters of mailto: URLs when using them as arguments to mail executable, which allows remote attackers to execute arbitrary programs.
CVE-2004-0473	Web browser doesn't filter "-" when invoking various commands, allowing command-line switches to be specified.
CVE-2004-0480	Mail client allows remote attackers to execute arbitrary code via a URI that uses a UNC network share pathname to provide an alternate configuration file.
CVE-2004-0489	SSH URI handler for web browser allows remote attackers to execute arbitrary code or conduct port forwarding via the a command line option.
CVE-2004-0411	Web browser doesn't filter "-" when invoking various commands, allowing command-line switches to be specified.
CVE-2005-4699	Argument injection vulnerability in TellMe 1.2 and earlier allows remote attackers to modify command line arguments for the Whois program and obtain sensitive information via "--" style options in the q_Host parameter.
CVE-2006-1865	Beagle before 0.2.5 can produce certain insecure command lines to launch external helper applications while indexing, which allows attackers to execute arbitrary commands. NOTE: it is not immediately clear whether this issue involves argument injection, shell metacharacters, or other issues.
CVE-2006-2056	Argument injection vulnerability in Internet Explorer 6 for Windows XP SP2 allows user-assisted remote attackers to modify command line arguments to an invoked mail client via " (double quote) characters in a mailto: scheme handler, as demonstrated by launching Microsoft Outlook with an arbitrary filename as an attachment. NOTE: it is not clear whether this issue is implementation-specific or a problem in the Microsoft API.
CVE-2006-2057	Argument injection vulnerability in Mozilla Firefox 1.0.6 allows user-assisted remote attackers to modify command line arguments to an invoked mail client via " (double quote) characters in a mailto: scheme handler, as demonstrated by launching Microsoft Outlook with an arbitrary filename as an attachment. NOTE: it is not clear whether this issue is implementation-specific or a problem in the Microsoft API.
CVE-2006-2058	Argument injection vulnerability in Avant Browser 10.1 Build 17 allows user-assisted remote attackers to modify command line arguments to an invoked mail client via " (double quote) characters in a mailto: scheme handler, as demonstrated by launching Microsoft Outlook with an arbitrary filename as an attachment. NOTE: it is not clear whether this issue is implementation-specific or a problem in the Microsoft API.
CVE-2006-2312	Argument injection vulnerability in the URI handler in Skype 2.0..104 and 2.5..0 through 2.5.*.78 for Windows allows remote authorized attackers to download arbitrary files via a URL that contains certain command-line switches.
CVE-2006-3015	Argument injection vulnerability in WinSCP 3.8.1 build 328 allows remote attackers to upload or download arbitrary files via encoded spaces and double-quote characters in a scp or sftp URI.
CVE-2006-4692	Argument injection vulnerability in the Windows Object Packager (packager.exe) in Microsoft Windows XP SP1 and SP2 and Server 2003 SP1 and earlier allows remote user-assisted attackers to execute arbitrary commands via a crafted file with a "/" (slash) character in the filename of the Command Line property, followed by a valid file extension, which causes the command before the slash to be executed, aka "Object Packager Dialogue Spoofing Vulnerability."
CVE-2006-6597	Argument injection vulnerability in HyperAccess 8.4 allows user-assisted remote attackers to execute arbitrary vbscript and commands via the /r option in a telnet:// URI, which is configured to use hawin32.exe.
CVE-2007-0882	Argument injection vulnerability in the telnet daemon (in.telnetd) in Solaris 10 and 11 (SunOS 5.10 and 5.11) misinterprets certain client "-f" sequences as valid requests for the login program to skip authentication, which allows remote attackers to log into certain accounts, as demonstrated by the bin account.
CVE-2001-1246	Language interpreter's mail function accepts another argument that is concatenated to a string used in a dangerous popen() call. Since there is no neutralization of this argument, both OS Command Injection (CWE-78) and Argument Injection (CWE-88) are possible.
CVE-2019-13475	Argument injection allows execution of arbitrary commands by injecting a "-exec" option, which is executed by the command.
CVE-2016-10033	Argument injection in mail-processing function allows writing unxpected files and executing programs using tecnically-valid email addresses that insert "-o" and "-X" switches.

Weakness Ordinalities

Ordinality	Description
Primary	(where the weakness exists independent of other weaknesses)

Detection Methods

Method

Details

Automated Static Analysis

Effectiveness: High

Affected Resources

System Process

Memberships

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	741	CERT C Secure Coding Standard (2008) Chapter 8 - Characters and Strings (STR)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	744	CERT C Secure Coding Standard (2008) Chapter 11 - Environment (ENV)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	810	OWASP Top Ten 2010 Category A1 - Injection
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	875	CERT C++ Secure Coding Section 07 - Characters and Strings (STR)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	878	CERT C++ Secure Coding Section 10 - Environment (ENV)
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	884	CWE Cross-section
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	929	OWASP Top Ten 2013 Category A1 - Injection
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	990	SFP Secondary Cluster: Tainted Input to Command
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1027	OWASP Top Ten 2017 Category A1 - Injection
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1165	SEI CERT C Coding Standard - Guidelines 10. Environment (ENV)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1347	OWASP Top Ten 2021 Category A03:2021 - Injection
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1409	Comprehensive Categorization: Injection

Vulnerability Mapping Notes

Usage	ALLOWED (this CWE ID may be used to map to real-world vulnerabilities)
Reason	Acceptable-Use
Rationale	This CWE entry is at the Base level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.
Comments	Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction.

Notes

Relationship

At one layer of abstraction, this can overlap other weaknesses that have whitespace problems, e.g. injection of javascript into attributes of HTML tags.

Taxonomy Mappings

Mapped Taxonomy Name	Node ID	Fit	Mapped Node Name
PLOVER			Argument Injection or Modification
CERT C Secure Coding	ENV03-C		Sanitize the environment when invoking external programs
CERT C Secure Coding	ENV33-C	Imprecise	Do not call system()
CERT C Secure Coding	STR02-C		Sanitize data passed to complex subsystems
WASC	30		Mail Command Injection

Related Attack Patterns

CAPEC-ID	Attack Pattern Name
CAPEC-137	Parameter Injection
CAPEC-174	Flash Parameter Injection
CAPEC-41	Using Meta-characters in E-mail Headers to Inject Malicious Payloads
CAPEC-460	HTTP Parameter Pollution (HPP)
CAPEC-88	OS Command Injection

References

[REF-859]	Steven Christey. "Argument injection issues". <https://seclists.org/bugtraq/2007/Feb/234ed>. (URL validated: 2023-04-07)
[REF-62]	Mark Dowd, John McDonald and Justin Schuh. "The Art of Software Security Assessment". Chapter 10, "The Argument Array", Page 567. 1st Edition. Addison Wesley. 2006.
[REF-1030]	Eldar Marcussen. "Security issues with using PHP's escapeshellarg". 2013-11-13. <https://baesystemsai.blogspot.com/2013/11/security-issues-with-using-phps.html>.
[REF-1249]	Dawid Golunski. "PHPMailer < 5.2.18 Remote Code Execution [CVE-2016-10033]". 2016-12-25. <https://legalhackers.com/advisories/PHPMailer-Exploit-Remote-Code-Exec-CVE-2016-10033-Vuln.html>.
[REF-1250]	Dawid Golunski. "Pwning PHP mail() function For Fun And RCE". 2017-05-03. <https://exploitbox.io/paper/Pwning-PHP-Mail-Function-For-Fun-And-RCE.html>.

Content History

Submissions
Submission Date	Submitter	Organization
2006-07-19 (CWE Draft 3, 2006-07-19)	PLOVER
2006-07-19 (CWE Draft 3, 2006-07-19)
Contributions
Contribution Date	Contributor	Organization
2021-05-28	Anonymous External Contributor
2021-05-28	Identified inappropriate demonstrative example, suggested new observed example, applicable language.
Modifications
Modification Date	Modifier	Organization
2024-07-16 (CWE 4.15, 2024-07-16)	CWE Content Team	MITRE
2024-07-16 (CWE 4.15, 2024-07-16)	updated Observed_Examples
2023-06-29	CWE Content Team	MITRE
2023-06-29	updated Mapping_Notes
2023-04-27	CWE Content Team	MITRE
2023-04-27	updated Description, Detection_Factors, References, Relationships, Time_of_Introduction
2023-01-31	CWE Content Team	MITRE
2023-01-31	updated Description, Potential_Mitigations
2022-10-13	CWE Content Team	MITRE
2022-10-13	updated Observed_Examples
2022-04-28	CWE Content Team	MITRE
2022-04-28	updated Applicable_Platforms, Demonstrative_Examples, Observed_Examples, References
2021-10-28	CWE Content Team	MITRE
2021-10-28	updated Relationships
2020-12-10	CWE Content Team	MITRE
2020-12-10	updated Relationships
2020-08-20	CWE Content Team	MITRE
2020-08-20	updated Relationships
2020-06-25	CWE Content Team	MITRE
2020-06-25	updated Potential_Mitigations
2020-02-24	CWE Content Team	MITRE
2020-02-24	updated Potential_Mitigations, Relationships
2019-09-23	CWE Content Team	MITRE
2019-09-23	updated Description, Name, Observed_Examples, Potential_Mitigations
2019-09-19	CWE Content Team	MITRE
2019-09-19	updated Description, Name, References, Relationships
2019-06-20	CWE Content Team	MITRE
2019-06-20	updated Related_Attack_Patterns, Relationships
2019-01-03	CWE Content Team	MITRE
2019-01-03	updated Relationships
2018-03-27	CWE Content Team	MITRE
2018-03-27	updated Relationships
2017-11-08	CWE Content Team	MITRE
2017-11-08	updated Applicable_Platforms, Causal_Nature, Modes_of_Introduction, Relationships, Taxonomy_Mappings
2015-12-07	CWE Content Team	MITRE
2015-12-07	updated Demonstrative_Examples, Relationships
2014-07-30	CWE Content Team	MITRE
2014-07-30	updated Relationships
2014-06-23	CWE Content Team	MITRE
2014-06-23	updated Relationships
2012-10-30	CWE Content Team	MITRE
2012-10-30	updated Potential_Mitigations
2012-05-11	CWE Content Team	MITRE
2012-05-11	updated Common_Consequences, Demonstrative_Examples, Observed_Examples, References, Related_Attack_Patterns, Relationships
2011-09-13	CWE Content Team	MITRE
2011-09-13	updated Relationships, Taxonomy_Mappings
2011-06-01	CWE Content Team	MITRE
2011-06-01	updated Common_Consequences
2010-09-27	CWE Content Team	MITRE
2010-09-27	updated Relationships
2010-06-21	CWE Content Team	MITRE
2010-06-21	updated Observed_Examples, Relationships
2010-04-05	CWE Content Team	MITRE
2010-04-05	updated Related_Attack_Patterns
2010-02-16	CWE Content Team	MITRE
2010-02-16	updated Potential_Mitigations, Relationships, Taxonomy_Mappings
2009-10-29	CWE Content Team	MITRE
2009-10-29	updated Observed_Examples
2009-07-27	CWE Content Team	MITRE
2009-07-27	updated Other_Notes, Relationship_Notes
2008-11-24	CWE Content Team	MITRE
2008-11-24	updated Observed_Examples, Relationships, Taxonomy_Mappings
2008-09-08	CWE Content Team	MITRE
2008-09-08	updated Relationships, Other_Notes, Taxonomy_Mappings, Weakness_Ordinalities
2008-07-01	Eric Dalci	Cigital
2008-07-01	updated Time_of_Introduction
Previous Entry Names
Change Date	Previous Entry Name
2019-09-19	Argument Injection or Modification
2019-09-23	Improper Delimitation of Arguments in a Command ('Argument Injection')

Weakness ID: 78

View customized information:

Description

Extended Description

This weakness can lead to a vulnerability in environments in which the attacker does not have direct access to the operating system, such as in web applications. Alternately, if the weakness occurs in a privileged program, it could allow the attacker to specify commands that normally would not be accessible, or to call alternate commands with privileges that the attacker does not have. The problem is exacerbated if the compromised process does not follow the principle of least privilege, because the attacker-controlled commands may run with special system privileges that increases the amount of damage.

There are at least two subtypes of OS command injection:

The application intends to execute a single, fixed program that is under its own control. It intends to use externally-supplied inputs as arguments to that program. For example, the program might use system("nslookup [HOSTNAME]") to run nslookup and allow the user to supply a HOSTNAME, which is used as an argument. Attackers cannot prevent nslookup from executing. However, if the program does not remove command separators from the HOSTNAME argument, attackers could place the separators into the arguments, which allows them to execute their own program after nslookup has finished executing.
The application accepts an input that it uses to fully select which program to run, as well as which commands to use. The application simply redirects this entire command to the operating system. For example, the program might use "exec([COMMAND])" to execute the [COMMAND] that was supplied by the user. If the COMMAND is under attacker control, then the attacker can execute arbitrary commands or programs. If the command is being executed using functions like exec() and CreateProcess(), the attacker might not be able to combine multiple commands together in the same line.

From a weakness standpoint, these variants represent distinct programmer errors. In the first variant, the programmer clearly intends that input from untrusted parties will be part of the arguments in the command to be executed. In the second variant, the programmer does not intend for the command to be accessible to any untrusted party, but the programmer probably has not accounted for alternate ways in which malicious attackers can provide input.

Alternate Terms

Shell injection
Shell metacharacters
OS Command Injection

Common Consequences

Impact

Details

Execute Unauthorized Code or Commands; DoS: Crash, Exit, or Restart; Read Files or Directories; Modify Files or Directories; Read Application Data; Modify Application Data; Hide Activities

Scope: Confidentiality, Integrity, Availability, Non-Repudiation

Attackers could execute unauthorized operating system commands, which could then be used to disable the product, or read and modify data for which the attacker does not have permissions to access directly. Since the targeted application is directly executing the commands instead of the attacker, any malicious activities may appear to come from the application or the application's owner.

Potential Mitigations

Phase(s)	Mitigation
Architecture and Design	If at all possible, use library calls rather than external processes to recreate the desired functionality.
Architecture and Design; Operation	Strategy: Sandbox or Jail Run the code in a "jail" or similar sandbox environment that enforces strict boundaries between the process and the operating system. This may effectively restrict which files can be accessed in a particular directory or which commands can be executed by the software. OS-level examples include the Unix chroot jail, AppArmor, and SELinux. In general, managed code may provide some protection. For example, java.io.FilePermission in the Java SecurityManager allows the software to specify restrictions on file operations. This may not be a feasible solution, and it only limits the impact to the operating system; the rest of the application may still be subject to compromise. Be careful to avoid CWE-243 and other weaknesses related to jails. Effectiveness: Limited Note: The effectiveness of this mitigation depends on the prevention capabilities of the specific sandbox or jail being used and might only help to reduce the scope of an attack, such as restricting the attacker to certain system calls or limiting the portion of the file system that can be accessed.
Architecture and Design	Strategy: Attack Surface Reduction For any data that will be used to generate a command to be executed, keep as much of that data out of external control as possible. For example, in web applications, this may require storing the data locally in the session's state instead of sending it out to the client in a hidden form field.
Architecture and Design	For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.
Architecture and Design	Strategy: Libraries or Frameworks Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, consider using the ESAPI Encoding control [REF-45] or a similar tool, library, or framework. These will help the programmer encode outputs in a manner less prone to error.
Implementation	Strategy: Output Encoding While it is risky to use dynamically-generated query strings, code, or commands that mix control and data together, sometimes it may be unavoidable. Properly quote arguments and escape any special characters within those arguments. The most conservative approach is to escape or filter all characters that do not pass an extremely strict allowlist (such as everything that is not alphanumeric or white space). If some special characters are still needed, such as white space, wrap each argument in quotes after the escaping/filtering step. Be careful of argument injection (CWE-88).
Implementation	If the program to be executed allows arguments to be specified within an input file or from standard input, then consider using that mode to pass arguments instead of the command line.
Architecture and Design	Strategy: Parameterization If available, use structured mechanisms that automatically enforce the separation between data and code. These mechanisms may be able to provide the relevant quoting, encoding, and validation automatically, instead of relying on the developer to provide this capability at every point where output is generated. Some languages offer multiple functions that can be used to invoke commands. Where possible, identify any function that invokes a command shell using a single string, and replace it with a function that requires individual arguments. These functions typically perform appropriate quoting and filtering of arguments. For example, in C, the system() function accepts a string that contains the entire command to be executed, whereas execl(), execve(), and others require an array of strings, one for each argument. In Windows, CreateProcess() only accepts one command at a time. In Perl, if system() is provided with an array of arguments, then it will quote each of the arguments.
Implementation	Strategy: Input Validation Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does. When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue." Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright. When constructing OS command strings, use stringent allowlists that limit the character set based on the expected value of the parameter in the request. This will indirectly limit the scope of an attack, but this technique is less important than proper output encoding and escaping. Note that proper output encoding, escaping, and quoting is the most effective solution for preventing OS command injection, although input validation may provide some defense-in-depth. This is because it effectively limits what will appear in output. Input validation will not always prevent OS command injection, especially if you are required to support free-form text fields that could contain arbitrary characters. For example, when invoking a mail program, you might need to allow the subject field to contain otherwise-dangerous inputs like ";" and ">" characters, which would need to be escaped or otherwise handled. In this case, stripping the character might reduce the risk of OS command injection, but it would produce incorrect behavior because the subject field would not be recorded as the user intended. This might seem to be a minor inconvenience, but it could be more important when the program relies on well-structured subject lines in order to pass messages to other components. Even if you make a mistake in your validation (such as forgetting one out of 100 input fields), appropriate encoding is still likely to protect you from injection-based attacks. As long as it is not done in isolation, input validation is still a useful technique, since it may significantly reduce your attack surface, allow you to detect some attacks, and provide other security benefits that proper encoding does not address.
Architecture and Design	Strategy: Enforcement by Conversion When the set of acceptable objects, such as filenames or URLs, is limited or known, create a mapping from a set of fixed input values (such as numeric IDs) to the actual filenames or URLs, and reject all other inputs.
Operation	Strategy: Compilation or Build Hardening Run the code in an environment that performs automatic taint propagation and prevents any command execution that uses tainted variables, such as Perl's "-T" switch. This will force the program to perform validation steps that remove the taint, although you must be careful to correctly validate your inputs so that you do not accidentally mark dangerous inputs as untainted (see CWE-183 and CWE-184).
Operation	Strategy: Environment Hardening Run the code in an environment that performs automatic taint propagation and prevents any command execution that uses tainted variables, such as Perl's "-T" switch. This will force the program to perform validation steps that remove the taint, although you must be careful to correctly validate your inputs so that you do not accidentally mark dangerous inputs as untainted (see CWE-183 and CWE-184).
Implementation	Ensure that error messages only contain minimal details that are useful to the intended audience and no one else. The messages need to strike the balance between being too cryptic (which can confuse users) or being too detailed (which may reveal more than intended). The messages should not reveal the methods that were used to determine the error. Attackers can use detailed information to refine or optimize their original attack, thereby increasing their chances of success. If errors must be captured in some detail, record them in log messages, but consider what could occur if the log messages can be viewed by attackers. Highly sensitive information such as passwords should never be saved to log files. Avoid inconsistent messaging that might accidentally tip off an attacker about internal state, such as whether a user account exists or not. In the context of OS Command Injection, error information passed back to the user might reveal whether an OS command is being executed and possibly which command is being used.
Operation	Strategy: Sandbox or Jail Use runtime policy enforcement to create an allowlist of allowable commands, then prevent use of any command that does not appear in the allowlist. Technologies such as AppArmor are available to do this.
Operation	Strategy: Firewall Use an application firewall that can detect attacks against this weakness. It can be beneficial in cases in which the code cannot be fixed (because it is controlled by a third party), as an emergency prevention measure while more comprehensive software assurance measures are applied, or to provide defense in depth. Effectiveness: Moderate Note: An application firewall might not cover all possible input vectors. In addition, attack techniques might be available to bypass the protection mechanism, such as using malformed inputs that can still be processed by the component that receives those inputs. Depending on functionality, an application firewall might inadvertently reject or modify legitimate requests. Finally, some manual effort may be required for customization.
Architecture and Design; Operation	Strategy: Environment Hardening Run your code using the lowest privileges that are required to accomplish the necessary tasks [REF-76]. If possible, create isolated accounts with limited privileges that are only used for a single task. That way, a successful attack will not immediately give the attacker access to the rest of the software or its environment. For example, database applications rarely need to run as the database administrator, especially in day-to-day operations.
Operation; Implementation	Strategy: Environment Hardening When using PHP, configure the application so that it does not use register_globals. During implementation, develop the application so that it does not rely on this feature, but be wary of implementing a register_globals emulation that is subject to weaknesses such as CWE-95, CWE-621, and similar issues.

Relationships

Relevant to the view "Research Concepts" (View-1000)

Nature	Type	ID	Name
ChildOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	77	Improper Neutralization of Special Elements used in a Command ('Command Injection')
CanAlsoBe	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	88	Improper Neutralization of Argument Delimiters in a Command ('Argument Injection')
CanFollow	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	184	Incomplete List of Disallowed Inputs

Relevant to the view "Software Development" (View-699)

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	137	Data Neutralization Issues

Relevant to the view "Weaknesses for Simplified Mapping of Published Vulnerabilities" (View-1003)

Nature	Type	ID	Name
ChildOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	74	Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')

Relevant to the view "Architectural Concepts" (View-1008)

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1019	Validate Inputs

Relevant to the view "CISQ Quality Measures (2020)" (View-1305)

Nature	Type	ID	Name
ChildOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	77	Improper Neutralization of Special Elements used in a Command ('Command Injection')

Relevant to the view "CISQ Data Protection Measures" (View-1340)

Nature	Type	ID	Name
ChildOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	77	Improper Neutralization of Special Elements used in a Command ('Command Injection')

Modes Of Introduction

Phase	Note
Implementation	REALIZATION: This weakness is caused during implementation of an architectural security tactic.

Applicable Platforms

Languages

Class: Not Language-Specific (Undetermined Prevalence)

Likelihood Of Exploit

High

Demonstrative Examples

Example 1

This example code intends to take the name of a user and list the contents of that user's home directory. It is subject to the first variant of OS command injection.

(bad code)

Example Language: PHP

$userName = $_POST["user"];
$command = 'ls -l /home/' . $userName;
system($command);

The $userName variable is not checked for malicious input. An attacker could set the $userName variable to an arbitrary OS command such as:

(attack code)

;rm -rf /

Which would result in $command being:

(result)

ls -l /home/;rm -rf /

Since the semi-colon is a command separator in Unix, the OS would first execute the ls command, then the rm command, deleting the entire file system.

Also note that this example code is vulnerable to Path Traversal (CWE-22) and Untrusted Search Path (CWE-426) attacks.

Example 2

The following simple program accepts a filename as a command line argument and displays the contents of the file back to the user. The program is installed setuid root because it is intended for use as a learning tool to allow system administrators in-training to inspect privileged system files without giving them the ability to modify them or damage the system.

(bad code)

Example Language: C

int main(int argc, char** argv) {

char cmd[CMD_MAX] = "/usr/bin/cat ";
strcat(cmd, argv[1]);
system(cmd);

}

Because the program runs with root privileges, the call to system() also executes with root privileges. If a user specifies a standard filename, the call works as expected. However, if an attacker passes a string of the form ";rm -rf /", then the call to system() fails to execute cat due to a lack of arguments and then plows on to recursively delete the contents of the root partition.

Note that if argv[1] is a very long argument, then this issue might also be subject to a buffer overflow (CWE-120).

Example 3

This example is a web application that intends to perform a DNS lookup of a user-supplied domain name. It is subject to the first variant of OS command injection.

(bad code)

Example Language: Perl

use CGI qw(:standard);
$name = param('name');
$nslookup = "/path/to/nslookup";
print header;
if (open($fh, "$nslookup $name|")) {

while (<$fh>) {

print escapeHTML($_);
print "<br>\n";

}
close($fh);

}

Suppose an attacker provides a domain name like this:

(attack code)

cwe.mitre.org%20%3B%20/bin/ls%20-l

The "%3B" sequence decodes to the ";" character, and the %20 decodes to a space. The open() statement would then process a string like this:

(result)

/path/to/nslookup cwe.mitre.org ; /bin/ls -l

As a result, the attacker executes the "/bin/ls -l" command and gets a list of all the files in the program's working directory. The input could be replaced with much more dangerous commands, such as installing a malicious program on the server.

Example 4

The example below reads the name of a shell script to execute from the system properties. It is subject to the second variant of OS command injection.

(bad code)

Example Language: Java

String script = System.getProperty("SCRIPTNAME");
if (script != null)

System.exec(script);

If an attacker has control over this property, then they could modify the property to point to a dangerous program.

Example 5

In the example below, a method is used to transform geographic coordinates from latitude and longitude format to UTM format. The method gets the input coordinates from a user through a HTTP request and executes a program local to the application server that performs the transformation. The method passes the latitude and longitude coordinates as a command-line option to the external program and will perform some processing to retrieve the results of the transformation and return the resulting UTM coordinates.

(bad code)

Example Language: Java

public String coordinateTransformLatLonToUTM(String coordinates)
{

String utmCoords = null;
try {

String latlonCoords = coordinates;
Runtime rt = Runtime.getRuntime();
Process exec = rt.exec("cmd.exe /C latlon2utm.exe -" + latlonCoords);
// process results of coordinate transform

// ...

}
catch(Exception e) {...}
return utmCoords;

}

However, the method does not verify that the contents of the coordinates input parameter includes only correctly-formatted latitude and longitude coordinates. If the input coordinates were not validated prior to the call to this method, a malicious user could execute another program local to the application server by appending '&' followed by the command for another program to the end of the coordinate string. The '&' instructs the Windows operating system to execute another program.

Example 6

The following code is from an administrative web application designed to allow users to kick off a backup of an Oracle database using a batch-file wrapper around the rman utility and then run a cleanup.bat script to delete some temporary files. The script rmanDB.bat accepts a single command line parameter, which specifies what type of backup to perform. Because access to the database is restricted, the application runs the backup as a privileged user.

(bad code)

Example Language: Java

...
String btype = request.getParameter("backuptype");
String cmd = new String("cmd.exe /K \"

c:\\util\\rmanDB.bat "
+btype+
"&&c:\\utl\\cleanup.bat\"")

System.Runtime.getRuntime().exec(cmd);
...

The problem here is that the program does not do any validation on the backuptype parameter read from the user. Typically the Runtime.exec() function will not execute multiple commands, but in this case the program first runs the cmd.exe shell in order to run multiple commands with a single call to Runtime.exec(). Once the shell is invoked, it will happily execute multiple commands separated by two ampersands. If an attacker passes a string of the form "& del c:\\dbms\\*.*", then the application will execute this command along with the others specified by the program. Because of the nature of the application, it runs with the privileges necessary to interact with the database, which means whatever command the attacker injects will run with those privileges as well.

Example 7

The following code is a wrapper around the UNIX command cat which prints the contents of a file to standard out. It is also injectable:

(bad code)

Example Language: C

#include <stdio.h>
#include <unistd.h>

int main(int argc, char **argv) {

char cat[] = "cat ";
char *command;
size_t commandLength;

commandLength = strlen(cat) + strlen(argv[1]) + 1;
command = (char *) malloc(commandLength);
strncpy(command, cat, commandLength);
strncat(command, argv[1], (commandLength - strlen(cat)) );

system(command);
return (0);

}

Used normally, the output is simply the contents of the file requested, such as Story.txt:

(informative)

./catWrapper Story.txt

(result)

When last we left our heroes...

However, if the provided argument includes a semicolon and another command, such as:

(attack code)

Story.txt; ls

Then the "ls" command is executed by catWrapper with no complaint:

(result)

./catWrapper Story.txt; ls

Two commands would then be executed: catWrapper, then ls. The result might look like:

(result)

When last we left our heroes...
Story.txt
SensitiveFile.txt
PrivateData.db
a.out*

If catWrapper had been set to have a higher privilege level than the standard user, arbitrary commands could be executed with that higher privilege.

Selected Observed Examples

Reference	Description
CVE-2020-10987	OS command injection in Wi-Fi router, as exploited in the wild per CISA KEV.
CVE-2020-10221	Template functionality in network configuration management tool allows OS command injection, as exploited in the wild per CISA KEV.
CVE-2020-9054	Chain: improper input validation (CWE-20) in username parameter, leading to OS command injection (CWE-78), as exploited in the wild per CISA KEV.
CVE-1999-0067	Canonical example of OS command injection. CGI program does not neutralize "\|" metacharacter when invoking a phonebook program.
CVE-2001-1246	Language interpreter's mail function accepts another argument that is concatenated to a string used in a dangerous popen() call. Since there is no neutralization of this argument, both OS Command Injection (CWE-78) and Argument Injection (CWE-88) are possible.
CVE-2002-0061	Web server allows command execution using "\|" (pipe) character.
CVE-2003-0041	FTP client does not filter "\|" from filenames returned by the server, allowing for OS command injection.
CVE-2008-2575	Shell metacharacters in a filename in a ZIP archive
CVE-2002-1898	Shell metacharacters in a telnet:// link are not properly handled when the launching application processes the link.
CVE-2008-4304	OS command injection through environment variable.
CVE-2008-4796	OS command injection through https:// URLs
CVE-2007-3572	Chain: incomplete denylist for OS command injection
CVE-2012-1988	Product allows remote users to execute arbitrary commands by creating a file whose pathname contains shell metacharacters.

Detection Methods

Method	Details
Automated Static Analysis	This weakness can often be detected using automated static analysis tools. Many modern tools use data flow analysis or constraint-based techniques to minimize the number of false positives. Automated static analysis might not be able to recognize when proper input validation is being performed, leading to false positives - i.e., warnings that do not have any security consequences or require any code changes. Automated static analysis might not be able to detect the usage of custom API functions or third-party libraries that indirectly invoke OS commands, leading to false negatives - especially if the API/library code is not available for analysis. Note:This is not a perfect solution, since 100% accuracy and coverage are not feasible.
Automated Dynamic Analysis	This weakness can be detected using dynamic tools and techniques that interact with the product using large test suites with many diverse inputs, such as fuzz testing (fuzzing), robustness testing, and fault injection. The product's operation may slow down, but it should not become unstable, crash, or generate incorrect results. Effectiveness: Moderate
Manual Static Analysis	Since this weakness does not typically appear frequently within a single software package, manual white box techniques may be able to provide sufficient code coverage and reduction of false positives if all potentially-vulnerable operations can be assessed within limited time constraints. Effectiveness: High
Automated Static Analysis - Binary or Bytecode	According to SOAR, the following detection techniques may be useful: Highly cost effective: Bytecode Weakness Analysis - including disassembler + source code weakness analysis Binary Weakness Analysis - including disassembler + source code weakness analysis Effectiveness: High
Dynamic Analysis with Automated Results Interpretation	According to SOAR, the following detection techniques may be useful: Cost effective for partial coverage: Web Application Scanner Web Services Scanner Database Scanners Effectiveness: SOAR Partial
Dynamic Analysis with Manual Results Interpretation	According to SOAR, the following detection techniques may be useful: Cost effective for partial coverage: Fuzz Tester Framework-based Fuzzer Effectiveness: SOAR Partial
Manual Static Analysis - Source Code	According to SOAR, the following detection techniques may be useful: Highly cost effective: Manual Source Code Review (not inspections) Cost effective for partial coverage: Focused Manual Spotcheck - Focused manual analysis of source Effectiveness: High
Automated Static Analysis - Source Code	According to SOAR, the following detection techniques may be useful: Highly cost effective: Source code Weakness Analyzer Context-configured Source Code Weakness Analyzer Effectiveness: High
Architecture or Design Review	According to SOAR, the following detection techniques may be useful: Highly cost effective: Formal Methods / Correct-By-Construction Cost effective for partial coverage: Inspection (IEEE 1028 standard) (can apply to requirements, design, source code, etc.) Effectiveness: High

Functional Areas

Program Invocation

Affected Resources

System Process

Memberships

Nature	Type	ID	Name
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	635	Weaknesses Originally Used by NVD from 2008 to 2016
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	714	OWASP Top Ten 2007 Category A3 - Malicious File Execution
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	727	OWASP Top Ten 2004 Category A6 - Injection Flaws
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	741	CERT C Secure Coding Standard (2008) Chapter 8 - Characters and Strings (STR)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	744	CERT C Secure Coding Standard (2008) Chapter 11 - Environment (ENV)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	751	2009 Top 25 - Insecure Interaction Between Components
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	801	2010 Top 25 - Insecure Interaction Between Components
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	810	OWASP Top Ten 2010 Category A1 - Injection
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	845	The CERT Oracle Secure Coding Standard for Java (2011) Chapter 2 - Input Validation and Data Sanitization (IDS)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	864	2011 Top 25 - Insecure Interaction Between Components
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	875	CERT C++ Secure Coding Section 07 - Characters and Strings (STR)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	878	CERT C++ Secure Coding Section 10 - Environment (ENV)
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	884	CWE Cross-section
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	929	OWASP Top Ten 2013 Category A1 - Injection
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	990	SFP Secondary Cluster: Tainted Input to Command
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1027	OWASP Top Ten 2017 Category A1 - Injection
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1131	CISQ Quality Measures (2016) - Security
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1134	SEI CERT Oracle Secure Coding Standard for Java - Guidelines 00. Input Validation and Data Sanitization (IDS)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1165	SEI CERT C Coding Standard - Guidelines 10. Environment (ENV)
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1200	Weaknesses in the 2019 CWE Top 25 Most Dangerous Software Errors
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1337	Weaknesses in the 2021 CWE Top 25 Most Dangerous Software Weaknesses
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1347	OWASP Top Ten 2021 Category A03:2021 - Injection
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1350	Weaknesses in the 2020 CWE Top 25 Most Dangerous Software Weaknesses
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1387	Weaknesses in the 2022 CWE Top 25 Most Dangerous Software Weaknesses
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1409	Comprehensive Categorization: Injection
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1425	Weaknesses in the 2023 CWE Top 25 Most Dangerous Software Weaknesses
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1430	Weaknesses in the 2024 CWE Top 25 Most Dangerous Software Weaknesses

Vulnerability Mapping Notes

Usage	ALLOWED (this CWE ID may be used to map to real-world vulnerabilities)
Reason	Acceptable-Use
Rationale	This CWE entry is at the Base level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.
Comments	Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction.

Notes

Terminology

The "OS command injection" phrase carries different meanings to different people. For some people, it only refers to cases in which the attacker injects command separators into arguments for an application-controlled program that is being invoked. For some people, it refers to any type of attack that can allow the attacker to execute OS commands of their own choosing. This usage could include untrusted search path weaknesses (CWE-426) that cause the application to find and execute an attacker-controlled program. Further complicating the issue is the case when argument injection (CWE-88) allows alternate command-line switches or options to be inserted into the command line, such as an "-exec" switch whose purpose may be to execute the subsequent argument as a command (this -exec switch exists in the UNIX "find" command, for example). In this latter case, however, CWE-88 could be regarded as the primary weakness in a chain with CWE-78.

Research Gap

More investigation is needed into the distinction between the OS command injection variants, including the role with argument injection (CWE-88). Equivalent distinctions may exist in other injection-related problems such as SQL injection.

Taxonomy Mappings

Mapped Taxonomy Name	Node ID	Fit	Mapped Node Name
PLOVER			OS Command Injection
OWASP Top Ten 2007	A3	CWE More Specific	Malicious File Execution
OWASP Top Ten 2004	A6	CWE More Specific	Injection Flaws
CERT C Secure Coding	ENV03-C		Sanitize the environment when invoking external programs
CERT C Secure Coding	ENV33-C	CWE More Specific	Do not call system()
CERT C Secure Coding	STR02-C		Sanitize data passed to complex subsystems
WASC	31		OS Commanding
The CERT Oracle Secure Coding Standard for Java (2011)	IDS07-J		Do not pass untrusted, unsanitized data to the Runtime.exec() method
Software Fault Patterns	SFP24		Tainted input to command
OMG ASCSM	ASCSM-CWE-78

Related Attack Patterns

CAPEC-ID	Attack Pattern Name
CAPEC-108	Command Line Execution through SQL Injection
CAPEC-15	Command Delimiters
CAPEC-43	Exploiting Multiple Input Interpretation Layers
CAPEC-6	Argument Injection
CAPEC-88	OS Command Injection

References

[REF-140]	Greg Hoglund and Gary McGraw. "Exploiting Software: How to Break Code". Addison-Wesley. 2004-02-27. <https://www.amazon.com/Exploiting-Software-How-Break-Code/dp/0201786958>. (URL validated: 2023-04-07)
[REF-685]	Pascal Meunier. "Meta-Character Vulnerabilities". 2008-02-20. <https://web.archive.org/web/20100714032622/https://www.cs.purdue.edu/homes/cs390s/slides/week09.pdf>. (URL validated: 2023-04-07)
[REF-686]	Robert Auger. "OS Commanding". 2009-06. <http://projects.webappsec.org/w/page/13246950/OS%20Commanding>. (URL validated: 2023-04-07)
[REF-687]	Lincoln Stein and John Stewart. "The World Wide Web Security FAQ". chapter: "CGI Scripts". 2002-02-04. <https://www.w3.org/Security/Faq/wwwsf4.html>. (URL validated: 2023-04-07)
[REF-688]	Jordan Dimov, Cigital. "Security Issues in Perl Scripts". <https://www.cgisecurity.com/lib/sips.html>. (URL validated: 2023-04-07)
[REF-44]	Michael Howard, David LeBlanc and John Viega. "24 Deadly Sins of Software Security". "Sin 10: Command Injection." Page 171. McGraw-Hill. 2010.
[REF-690]	Frank Kim. "Top 25 Series - Rank 9 - OS Command Injection". SANS Software Security Institute. 2010-02-24. <https://www.sans.org/blog/top-25-series-rank-9-os-command-injection/>. (URL validated: 2023-04-07)
[REF-45]	OWASP. "OWASP Enterprise Security API (ESAPI) Project". <http://www.owasp.org/index.php/ESAPI>.
[REF-76]	Sean Barnum and Michael Gegick. "Least Privilege". 2005-09-14. <https://web.archive.org/web/20211209014121/https://www.cisa.gov/uscert/bsi/articles/knowledge/principles/least-privilege>. (URL validated: 2023-04-07)
[REF-62]	Mark Dowd, John McDonald and Justin Schuh. "The Art of Software Security Assessment". Chapter 8, "Shell Metacharacters", Page 425. 1st Edition. Addison Wesley. 2006.
[REF-962]	Object Management Group (OMG). "Automated Source Code Security Measure (ASCSM)". ASCSM-CWE-78. 2016-01. <http://www.omg.org/spec/ASCSM/1.0/>.
[REF-1449]	Cybersecurity and Infrastructure Security Agency. "Secure by Design Alert: Eliminating OS Command Injection Vulnerabilities". 2024-07-10. <https://www.cisa.gov/resources-tools/resources/secure-design-alert-eliminating-os-command-injection-vulnerabilities>. (URL validated: 2024-07-14)

Content History

Submissions
Submission Date	Submitter	Organization
2006-07-19 (CWE Draft 3, 2006-07-19)	PLOVER
2006-07-19 (CWE Draft 3, 2006-07-19)
Contributions
Contribution Date	Contributor	Organization
2024-02-29 (CWE 4.15, 2024-07-16)	Abhi Balakrishnan
2024-02-29 (CWE 4.15, 2024-07-16)	Provided diagram to improve CWE usability
Modifications
Modification Date	Modifier	Organization
2024-11-19 (CWE 4.16, 2024-11-19)	CWE Content Team	MITRE
2024-11-19 (CWE 4.16, 2024-11-19)	updated Relationships
2024-07-16 (CWE 4.15, 2024-07-16)	CWE Content Team	MITRE
2024-07-16 (CWE 4.15, 2024-07-16)	updated Alternate_Terms, Common_Consequences, Demonstrative_Examples, Description, Diagram, References
2023-06-29	CWE Content Team	MITRE
2023-06-29	updated Mapping_Notes, Relationships
2023-04-27	CWE Content Team	MITRE
2023-04-27	updated Detection_Factors, References, Relationships, Time_of_Introduction
2023-01-31	CWE Content Team	MITRE
2023-01-31	updated Common_Consequences, Description
2022-10-13	CWE Content Team	MITRE
2022-10-13	updated References
2022-06-28	CWE Content Team	MITRE
2022-06-28	updated Observed_Examples, Relationships
2022-04-28	CWE Content Team	MITRE
2022-04-28	updated Demonstrative_Examples
2021-10-28	CWE Content Team	MITRE
2021-10-28	updated Relationships
2021-07-20	CWE Content Team	MITRE
2021-07-20	updated Observed_Examples, Relationships
2020-12-10	CWE Content Team	MITRE
2020-12-10	updated Potential_Mitigations, Relationships
2020-08-20	CWE Content Team	MITRE
2020-08-20	updated Relationships
2020-06-25	CWE Content Team	MITRE
2020-06-25	updated Observed_Examples, Potential_Mitigations
2020-02-24	CWE Content Team	MITRE
2020-02-24	updated Potential_Mitigations, Relationships
2019-09-19	CWE Content Team	MITRE
2019-09-19	updated Relationships
2019-06-20	CWE Content Team	MITRE
2019-06-20	updated Relationships
2019-01-03	CWE Content Team	MITRE
2019-01-03	updated References, Relationships, Taxonomy_Mappings
2018-03-27	CWE Content Team	MITRE
2018-03-27	updated Relationships
2017-11-08	CWE Content Team	MITRE
2017-11-08	updated Modes_of_Introduction, References, Relationships, Taxonomy_Mappings, White_Box_Definitions
2015-12-07	CWE Content Team	MITRE
2015-12-07	updated Relationships
2014-07-30	CWE Content Team	MITRE
2014-07-30	updated Detection_Factors, Relationships, Taxonomy_Mappings
2014-06-23	CWE Content Team	MITRE
2014-06-23	updated Relationships
2014-02-18	CWE Content Team	MITRE
2014-02-18	updated Applicable_Platforms, Demonstrative_Examples, Terminology_Notes
2012-10-30	CWE Content Team	MITRE
2012-10-30	updated Observed_Examples, Potential_Mitigations
2012-05-11	CWE Content Team	MITRE
2012-05-11	updated Demonstrative_Examples, References, Relationships, Taxonomy_Mappings
2011-09-13	CWE Content Team	MITRE
2011-09-13	updated Potential_Mitigations, References, Relationships, Taxonomy_Mappings
2011-06-27	CWE Content Team	MITRE
2011-06-27	updated Relationships
2011-06-01	CWE Content Team	MITRE
2011-06-01	updated Common_Consequences, Relationships, Taxonomy_Mappings
2011-03-29	CWE Content Team	MITRE
2011-03-29	updated Demonstrative_Examples, Description
2010-12-13	CWE Content Team	MITRE
2010-12-13	updated Description, Potential_Mitigations
2010-09-27	CWE Content Team	MITRE
2010-09-27	updated Potential_Mitigations
2010-06-21	CWE Content Team	MITRE
2010-06-21	updated Common_Consequences, Description, Detection_Factors, Name, Observed_Examples, Potential_Mitigations, References, Relationships
2010-04-05	CWE Content Team	MITRE
2010-04-05	updated Potential_Mitigations
2010-02-16	CWE Content Team	MITRE
2010-02-16	updated Detection_Factors, Potential_Mitigations, References, Relationships, Taxonomy_Mappings
2009-12-28	CWE Content Team	MITRE
2009-12-28	updated Detection_Factors
2009-10-29	CWE Content Team	MITRE
2009-10-29	updated Observed_Examples, References
2009-07-27	CWE Content Team	MITRE
2009-07-27	updated Description, Name, White_Box_Definitions
2009-07-17	KDM Analytics
2009-07-17	Improved the White_Box_Definition
2009-05-27	CWE Content Team	MITRE
2009-05-27	updated Name, Related_Attack_Patterns
2009-03-10	CWE Content Team	MITRE
2009-03-10	updated Potential_Mitigations
2009-01-12	CWE Content Team	MITRE
2009-01-12	updated Common_Consequences, Demonstrative_Examples, Description, Likelihood_of_Exploit, Name, Observed_Examples, Other_Notes, Potential_Mitigations, Relationships, Research_Gaps, Terminology_Notes
2008-11-24	CWE Content Team	MITRE
2008-11-24	updated Observed_Examples, Relationships, Taxonomy_Mappings
2008-10-14	CWE Content Team	MITRE
2008-10-14	updated Description
2008-09-08	CWE Content Team	MITRE
2008-09-08	updated Relationships, Other_Notes, Taxonomy_Mappings
2008-08-15		Veracode
2008-08-15	Suggested OWASP Top Ten 2004 mapping
2008-08-01		KDM Analytics
2008-08-01	added/updated white box definitions
2008-07-01	Eric Dalci	Cigital
2008-07-01	updated Time_of_Introduction
2008-07-01	Sean Eidemiller	Cigital
2008-07-01	added/updated demonstrative examples
Previous Entry Names
Change Date	Previous Entry Name
2008-04-11	OS Command Injection
2009-01-12	Failure to Sanitize Data into an OS Command (aka 'OS Command Injection')
2009-05-27	Failure to Preserve OS Command Structure (aka 'OS Command Injection')
2009-07-27	Failure to Preserve OS Command Structure ('OS Command Injection')
2010-06-21	Improper Sanitization of Special Elements used in an OS Command ('OS Command Injection')

Weakness ID: 170

View customized information:

Description

The product does not terminate or incorrectly terminates a string or array with a null character or equivalent terminator.

Extended Description

Null termination errors frequently occur in two different ways. An off-by-one error could cause a null to be written out of bounds, leading to an overflow. Or, a program could use a strncpy() function call incorrectly, which prevents a null terminator from being added at all. Other scenarios are possible.

Common Consequences

Impact	Details
Read Memory; Execute Unauthorized Code or Commands	Scope: Confidentiality, Integrity, Availability The case of an omitted null character is the most dangerous of the possible issues. This will almost certainly result in information disclosure, and possibly a buffer overflow condition, which may be exploited to execute arbitrary code.
DoS: Crash, Exit, or Restart; Read Memory; DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory)	Scope: Confidentiality, Integrity, Availability If a null character is omitted from a string, then most string-copying functions will read data until they locate a null character, even outside of the intended boundaries of the string. This could: cause a crash due to a segmentation fault cause sensitive adjacent memory to be copied and sent to an outsider trigger a buffer overflow when the copy is being written to a fixed-size buffer.
Modify Memory; DoS: Crash, Exit, or Restart	Scope: Integrity, Availability Misplaced null characters may result in any number of security problems. The biggest issue is a subset of buffer overflow, and write-what-where conditions, where data corruption occurs from the writing of a null character over valid data, or even instructions. A randomly placed null character may put the system into an undefined state, and therefore make it prone to crashing. A misplaced null character may corrupt other data in memory.
Alter Execution Logic; Execute Unauthorized Code or Commands	Scope: Integrity, Confidentiality, Availability, Access Control, Other Should the null character corrupt the process flow, or affect a flag controlling access, it may lead to logical errors which allow for the execution of arbitrary code.

Potential Mitigations

Phase(s)	Mitigation
Requirements	Use a language that is not susceptible to these issues. However, be careful of null byte interaction errors (CWE-626) with lower-level constructs that may be written in a language that is susceptible.
Implementation	Ensure that all string functions used are understood fully as to how they append null characters. Also, be wary of off-by-one errors when appending nulls to the end of strings.
Implementation	If performance constraints permit, special code can be added that validates null-termination of string buffers, this is a rather naive and error-prone solution.
Implementation	Switch to bounded string manipulation functions. Inspect buffer lengths involved in the buffer overrun trace reported with the defect.
Implementation	Add code that fills buffers with nulls (however, the length of buffers still needs to be inspected, to ensure that the non null-terminated string is not written at the physical end of the buffer).

Relationships

Relevant to the view "Research Concepts" (View-1000)

Nature	Type	ID	Name
ChildOf	Pillar - a weakness that is the most abstract type of weakness and represents a theme for all class/base/variant weaknesses related to it. A Pillar is different from a Category as a Pillar is still technically a type of weakness that describes a mistake, while a Category represents a common characteristic used to group related things.	707	Improper Neutralization
PeerOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	463	Deletion of Data Structure Sentinel
PeerOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	464	Addition of Data Structure Sentinel
CanAlsoBe	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	147	Improper Neutralization of Input Terminators
CanFollow	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	193	Off-by-one Error
CanFollow	Pillar - a weakness that is the most abstract type of weakness and represents a theme for all class/base/variant weaknesses related to it. A Pillar is different from a Category as a Pillar is still technically a type of weakness that describes a mistake, while a Category represents a common characteristic used to group related things.	682	Incorrect Calculation
CanPrecede	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	120	Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
CanPrecede	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	126	Buffer Over-read

Relevant to the view "Software Development" (View-699)

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	137	Data Neutralization Issues

Relevant to the view "Seven Pernicious Kingdoms" (View-700)

Nature	Type	ID	Name
ChildOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	20	Improper Input Validation

Modes Of Introduction

Phase	Note
Implementation

Applicable Platforms

Languages

C (Undetermined Prevalence)

C++ (Undetermined Prevalence)

Likelihood Of Exploit

Medium

Demonstrative Examples

Example 1

The following code reads from cfgfile and copies the input into inputbuf using strcpy(). The code mistakenly assumes that inputbuf will always contain a NULL terminator.

(bad code)

Example Language: C

#define MAXLEN 1024
...
char *pathbuf[MAXLEN];
...
read(cfgfile,inputbuf,MAXLEN); //does not null terminate
strcpy(pathbuf,inputbuf); //requires null terminated input
...

The code above will behave correctly if the data read from cfgfile is null terminated on disk as expected. But if an attacker is able to modify this input so that it does not contain the expected NULL character, the call to strcpy() will continue copying from memory until it encounters an arbitrary NULL character. This will likely overflow the destination buffer and, if the attacker can control the contents of memory immediately following inputbuf, can leave the application susceptible to a buffer overflow attack.

Example 2

In the following code, readlink() expands the name of a symbolic link stored in pathname and puts the absolute path into buf. The length of the resulting value is then calculated using strlen().

(bad code)

Example Language: C

char buf[MAXPATH];
...
readlink(pathname, buf, MAXPATH);
int length = strlen(buf);
...

The code above will not always behave correctly as readlink() does not append a NULL byte to buf. Readlink() will stop copying characters once the maximum size of buf has been reached to avoid overflowing the buffer, this will leave the value buf not NULL terminated. In this situation, strlen() will continue traversing memory until it encounters an arbitrary NULL character further on down the stack, resulting in a length value that is much larger than the size of string. Readlink() does return the number of bytes copied, but when this return value is the same as stated buf size (in this case MAXPATH), it is impossible to know whether the pathname is precisely that many bytes long, or whether readlink() has truncated the name to avoid overrunning the buffer. In testing, vulnerabilities like this one might not be caught because the unused contents of buf and the memory immediately following it may be NULL, thereby causing strlen() to appear as if it is behaving correctly.

Example 3

While the following example is not exploitable, it provides a good example of how nulls can be omitted or misplaced, even when "safe" functions are used:

(bad code)

Example Language: C

#include <stdio.h>
#include <string.h>

int main() {

char longString[] = "String signifying nothing";
char shortString[16];

strncpy(shortString, longString, 16);
printf("The last character in shortString is: %c (%1$x)\n", shortString[15]);
return (0);

}

The above code gives the following output: "The last character in shortString is: n (6e)". So, the shortString array does not end in a NULL character, even though the "safe" string function strncpy() was used. The reason is that strncpy() does not impliciitly add a NULL character at the end of the string when the source is equal in length or longer than the provided size.

Selected Observed Examples

Reference	Description
CVE-2000-0312	Attacker does not null-terminate argv[] when invoking another program.
CVE-2003-0777	Interrupted step causes resultant lack of null termination.
CVE-2004-1072	Fault causes resultant lack of null termination, leading to buffer expansion.
CVE-2001-1389	Multiple vulnerabilities related to improper null termination.
CVE-2003-0143	Product does not null terminate a message buffer after snprintf-like call, leading to overflow.
CVE-2009-2523	Chain: product does not handle when an input string is not NULL terminated (CWE-170), leading to buffer over-read (CWE-125) or heap-based buffer overflow (CWE-122).

Weakness Ordinalities

Ordinality	Description
Resultant	(where the weakness is typically related to the presence of some other weaknesses)

Detection Methods

Method

Details

Automated Static Analysis

Effectiveness: High

Memberships

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	730	OWASP Top Ten 2004 Category A9 - Denial of Service
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	741	CERT C Secure Coding Standard (2008) Chapter 8 - Characters and Strings (STR)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	748	CERT C Secure Coding Standard (2008) Appendix - POSIX (POS)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	875	CERT C++ Secure Coding Section 07 - Characters and Strings (STR)
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	884	CWE Cross-section
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	973	SFP Secondary Cluster: Improper NULL Termination
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1161	SEI CERT C Coding Standard - Guidelines 07. Characters and Strings (STR)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1171	SEI CERT C Coding Standard - Guidelines 50. POSIX (POS)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1306	CISQ Quality Measures - Reliability
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1340	CISQ Data Protection Measures
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1407	Comprehensive Categorization: Improper Neutralization

Vulnerability Mapping Notes

Usage	ALLOWED (this CWE ID may be used to map to real-world vulnerabilities)
Reason	Acceptable-Use
Rationale	This CWE entry is at the Base level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.
Comments	Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction.

Notes

Relationship

Factors: this is usually resultant from other weaknesses such as off-by-one errors, but it can be primary to boundary condition violations such as buffer overflows. In buffer overflows, it can act as an expander for assumed-immutable data.

Relationship

Overlaps missing input terminator.

Applicable Platform

Conceptually, this does not just apply to the C language; any language or representation that involves a terminator could have this type of problem.

Maintenance

As currently described, this entry is more like a category than a weakness.

Taxonomy Mappings

Mapped Taxonomy Name	Node ID	Fit	Mapped Node Name
PLOVER			Improper Null Termination
7 Pernicious Kingdoms			String Termination Error
CLASP			Miscalculated null termination
OWASP Top Ten 2004	A9	CWE More Specific	Denial of Service
CERT C Secure Coding	POS30-C	CWE More Abstract	Use the readlink() function properly
CERT C Secure Coding	STR03-C		Do not inadvertently truncate a null-terminated byte string
CERT C Secure Coding	STR32-C	Exact	Do not pass a non-null-terminated character sequence to a library function that expects a string
Software Fault Patterns	SFP11		Improper Null Termination

Content History

Submissions
Submission Date	Submitter	Organization
2006-07-19 (CWE Draft 3, 2006-07-19)	PLOVER
2006-07-19 (CWE Draft 3, 2006-07-19)
Modifications
Modification Date	Modifier	Organization
2023-06-29	CWE Content Team	MITRE
2023-06-29	updated Mapping_Notes
2023-04-27	CWE Content Team	MITRE
2023-04-27	updated Detection_Factors, Relationships
2023-01-31	CWE Content Team	MITRE
2023-01-31	updated Description
2020-12-10	CWE Content Team	MITRE
2020-12-10	updated Relationships
2020-08-20	CWE Content Team	MITRE
2020-08-20	updated Relationships
2020-02-24	CWE Content Team	MITRE
2020-02-24	updated Relationships
2019-01-03	CWE Content Team	MITRE
2019-01-03	updated Relationships
2018-03-27	CWE Content Team	MITRE
2018-03-27	updated Demonstrative_Examples
2017-11-08	CWE Content Team	MITRE
2017-11-08	updated Causal_Nature, Observed_Examples, Relationships, Taxonomy_Mappings, White_Box_Definitions
2014-07-30	CWE Content Team	MITRE
2014-07-30	updated Relationships, Taxonomy_Mappings
2014-06-23	CWE Content Team	MITRE
2014-06-23	updated Observed_Examples
2012-05-11	CWE Content Team	MITRE
2012-05-11	updated Relationships
2011-09-13	CWE Content Team	MITRE
2011-09-13	updated Relationships, Taxonomy_Mappings
2011-06-01	CWE Content Team	MITRE
2011-06-01	updated Common_Consequences
2011-03-29	CWE Content Team	MITRE
2011-03-29	updated Common_Consequences
2009-10-29	CWE Content Team	MITRE
2009-10-29	updated Description
2009-07-27	CWE Content Team	MITRE
2009-07-27	updated Common_Consequences, Other_Notes, Potential_Mitigations, White_Box_Definitions
2009-07-17	KDM Analytics
2009-07-17	Improved the White_Box_Definition
2009-05-27	CWE Content Team	MITRE
2009-05-27	updated Demonstrative_Examples
2009-03-10	CWE Content Team	MITRE
2009-03-10	updated Common_Consequences
2008-11-24	CWE Content Team	MITRE
2008-11-24	updated Relationships, Taxonomy_Mappings
2008-09-08	CWE Content Team	MITRE
2008-09-08	updated Applicable_Platforms, Causal_Nature, Common_Consequences, Description, Likelihood_of_Exploit, Maintenance_Notes, Relationships, Other_Notes, Relationship_Notes, Taxonomy_Mappings, Weakness_Ordinalities
2008-08-01		KDM Analytics
2008-08-01	added/updated white box definitions
2008-07-01	Eric Dalci	Cigital
2008-07-01	updated Time_of_Introduction

Weakness ID: 41

View customized information:

Description

Extended Description

Path equivalence is usually employed in order to circumvent access controls expressed using an incomplete set of file name or file path representations. This is different from path traversal, wherein the manipulations are performed to generate a name for a different object.

Common Consequences

Impact	Details
Read Files or Directories; Modify Files or Directories; Bypass Protection Mechanism	Scope: Confidentiality, Integrity, Access Control An attacker may be able to traverse the file system to unintended locations and read or overwrite the contents of unexpected files. If the files are used for a security mechanism than an attacker may be able to bypass the mechanism.

Potential Mitigations

Phase(s)	Mitigation
Implementation	Strategy: Input Validation Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does. When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue." Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.
Implementation	Strategy: Output Encoding Use and specify an output encoding that can be handled by the downstream component that is reading the output. Common encodings include ISO-8859-1, UTF-7, and UTF-8. When an encoding is not specified, a downstream component may choose a different encoding, either by assuming a default encoding or automatically inferring which encoding is being used, which can be erroneous. When the encodings are inconsistent, the downstream component might treat some character or byte sequences as special, even if they are not special in the original encoding. Attackers might then be able to exploit this discrepancy and conduct injection attacks; they even might be able to bypass protection mechanisms that assume the original encoding is also being used by the downstream component.
Implementation	Strategy: Input Validation Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180). Make sure that the application does not decode the same input twice (CWE-174). Such errors could be used to bypass allowlist validation schemes by introducing dangerous inputs after they have been checked.

Relationships

Relevant to the view "Research Concepts" (View-1000)

Nature	Type	ID	Name
ChildOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	706	Use of Incorrectly-Resolved Name or Reference
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	42	Path Equivalence: 'filename.' (Trailing Dot)
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	44	Path Equivalence: 'file.name' (Internal Dot)
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	46	Path Equivalence: 'filename ' (Trailing Space)
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	47	Path Equivalence: ' filename' (Leading Space)
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	48	Path Equivalence: 'file name' (Internal Whitespace)
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	49	Path Equivalence: 'filename/' (Trailing Slash)
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	50	Path Equivalence: '//multiple/leading/slash'
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	51	Path Equivalence: '/multiple//internal/slash'
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	52	Path Equivalence: '/multiple/trailing/slash//'
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	53	Path Equivalence: '\multiple\\internal\backslash'
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	54	Path Equivalence: 'filedir\' (Trailing Backslash)
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	55	Path Equivalence: '/./' (Single Dot Directory)
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	56	Path Equivalence: 'filedir*' (Wildcard)
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	57	Path Equivalence: 'fakedir/../realdir/filename'
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	58	Path Equivalence: Windows 8.3 Filename
PeerOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	1289	Improper Validation of Unsafe Equivalence in Input
CanFollow	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	20	Improper Input Validation
CanFollow	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	73	External Control of File Name or Path
CanFollow	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	172	Encoding Error

Relevant to the view "Software Development" (View-699)

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1219	File Handling Issues

Modes Of Introduction

Phase	Note
Implementation

Applicable Platforms

Languages

Class: Not Language-Specific (Undetermined Prevalence)

Selected Observed Examples

Reference	Description
CVE-2000-1114	Source code disclosure using trailing dot
CVE-2002-1986	Source code disclosure using trailing dot
CVE-2004-2213	Source code disclosure using trailing dot or trailing encoding space "%20"
CVE-2005-3293	Source code disclosure using trailing dot
CVE-2004-0061	Bypass directory access restrictions using trailing dot in URL
CVE-2000-1133	Bypass directory access restrictions using trailing dot in URL
CVE-2001-1386	Bypass check for ".lnk" extension using ".lnk."
CVE-2001-0693	Source disclosure via trailing encoded space "%20"
CVE-2001-0778	Source disclosure via trailing encoded space "%20"
CVE-2001-1248	Source disclosure via trailing encoded space "%20"
CVE-2004-0280	Source disclosure via trailing encoded space "%20"
CVE-2005-0622	Source disclosure via trailing encoded space "%20"
CVE-2005-1656	Source disclosure via trailing encoded space "%20"
CVE-2002-1603	Source disclosure via trailing encoded space "%20"
CVE-2001-0054	Multi-Factor Vulnerability (MFV). directory traversal and other issues in FTP server using Web encodings such as "%20"; certain manipulations have unusual side effects.
CVE-2002-1451	Trailing space ("+" in query string) leads to source code disclosure.
CVE-2000-0293	Filenames with spaces allow arbitrary file deletion when the product does not properly quote them; some overlap with path traversal.
CVE-2001-1567	"+" characters in query string converted to spaces before sensitive file/extension (internal space), leading to bypass of access restrictions to the file.
CVE-2002-0253	Overlaps infoleak
CVE-2001-0446	Application server allows remote attackers to read source code for .jsp files by appending a / to the requested URL.
CVE-2004-0334	Bypass Basic Authentication for files using trailing "/"
CVE-2001-0893	Read sensitive files with trailing "/"
CVE-2001-0892	Web server allows remote attackers to view sensitive files under the document root (such as .htpasswd) via a GET request with a trailing /.
CVE-2004-1814	Directory traversal vulnerability in server allows remote attackers to read protected files via .. (dot dot) sequences in an HTTP request.
CVE-2002-1483	Read files with full pathname using multiple internal slash.
CVE-1999-1456	Server allows remote attackers to read arbitrary files via a GET request with more than one leading / (slash) character in the filename.
CVE-2004-0578	Server allows remote attackers to read arbitrary files via leading slash (//) characters in a URL request.
CVE-2002-0275	Server allows remote attackers to bypass authentication and read restricted files via an extra / (slash) in the requested URL.
CVE-2004-1032	Product allows local users to delete arbitrary files or create arbitrary empty files via a target filename with a large number of leading slash (/) characters.
CVE-2002-1238	Server allows remote attackers to bypass access restrictions for files via an HTTP request with a sequence of multiple / (slash) characters such as http://www.example.com///file/.
CVE-2004-1878	Product allows remote attackers to bypass authentication, obtain sensitive information, or gain access via a direct request to admin/user.pl preceded by // (double leading slash).
CVE-2005-1365	Server allows remote attackers to execute arbitrary commands via a URL with multiple leading "/" (slash) characters and ".." sequences.
CVE-2000-1050	Access directory using multiple leading slash.
CVE-2001-1072	Bypass access restrictions via multiple leading slash, which causes a regular expression to fail.
CVE-2004-0235	Archive extracts to arbitrary files using multiple leading slash in filenames in the archive.
CVE-2002-1078	Directory listings in web server using multiple trailing slash
CVE-2004-0847	ASP.NET allows remote attackers to bypass authentication for .aspx files in restricted directories via a request containing a (1) "\" (backslash) or (2) "%5C" (encoded backslash), aka "Path Validation Vulnerability."
CVE-2000-0004	Server allows remote attackers to read source code for executable files by inserting a . (dot) into the URL.
CVE-2002-0304	Server allows remote attackers to read password-protected files via a /./ in the HTTP request.
CVE-1999-1083	Possibly (could be a cleansing error)
CVE-2004-0815	"/./////etc" cleansed to ".///etc" then "/etc"
CVE-2002-0112	Server allows remote attackers to view password protected files via /./ in the URL.
CVE-2004-0696	List directories using desired path and "*"
CVE-2002-0433	List files in web server using "*.ext"
CVE-2001-1152	Proxy allows remote attackers to bypass denylist restrictions and connect to unauthorized web servers by modifying the requested URL, including (1) a // (double slash), (2) a /SUBDIR/.. where the desired file is in the parentdir, (3) a /./, or (4) URL-encoded characters.
CVE-2000-0191	application check access for restricted URL before canonicalization
CVE-2005-1366	CGI source disclosure using "dirname/../cgi-bin"
CVE-1999-0012	Multiple web servers allow restriction bypass using 8.3 names instead of long names
CVE-2001-0795	Source code disclosure using 8.3 file name.
CVE-2005-0471	Multi-Factor Vulnerability. Product generates temporary filenames using long filenames, which become predictable in 8.3 format.

Detection Methods

Method	Details
Automated Static Analysis - Binary or Bytecode	According to SOAR, the following detection techniques may be useful: Cost effective for partial coverage: Bytecode Weakness Analysis - including disassembler + source code weakness analysis Effectiveness: SOAR Partial
Manual Static Analysis - Binary or Bytecode	According to SOAR, the following detection techniques may be useful: Cost effective for partial coverage: Binary / Bytecode disassembler - then use manual analysis for vulnerabilities & anomalies Effectiveness: SOAR Partial
Dynamic Analysis with Automated Results Interpretation	According to SOAR, the following detection techniques may be useful: Cost effective for partial coverage: Web Application Scanner Web Services Scanner Database Scanners Effectiveness: SOAR Partial
Dynamic Analysis with Manual Results Interpretation	According to SOAR, the following detection techniques may be useful: Cost effective for partial coverage: Fuzz Tester Framework-based Fuzzer Effectiveness: SOAR Partial
Manual Static Analysis - Source Code	According to SOAR, the following detection techniques may be useful: Highly cost effective: Focused Manual Spotcheck - Focused manual analysis of source Manual Source Code Review (not inspections) Effectiveness: High
Automated Static Analysis - Source Code	According to SOAR, the following detection techniques may be useful: Cost effective for partial coverage: Source code Weakness Analyzer Context-configured Source Code Weakness Analyzer Effectiveness: SOAR Partial
Architecture or Design Review	According to SOAR, the following detection techniques may be useful: Highly cost effective: Formal Methods / Correct-By-Construction Cost effective for partial coverage: Inspection (IEEE 1028 standard) (can apply to requirements, design, source code, etc.) Effectiveness: High

Affected Resources

File or Directory

Memberships

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	723	OWASP Top Ten 2004 Category A2 - Broken Access Control
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	743	CERT C Secure Coding Standard (2008) Chapter 10 - Input Output (FIO)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	877	CERT C++ Secure Coding Section 09 - Input Output (FIO)
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	884	CWE Cross-section
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	981	SFP Secondary Cluster: Path Traversal
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1404	Comprehensive Categorization: File Handling

Vulnerability Mapping Notes

Usage	ALLOWED (this CWE ID may be used to map to real-world vulnerabilities)
Reason	Acceptable-Use
Rationale	This CWE entry is at the Base level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.
Comments	Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction.

Notes

Relationship

Some of these manipulations could be effective in path traversal issues, too.

Taxonomy Mappings

Mapped Taxonomy Name	Node ID	Fit	Mapped Node Name
PLOVER			Path Equivalence
CERT C Secure Coding	FIO02-C		Canonicalize path names originating from untrusted sources

Related Attack Patterns

CAPEC-ID	Attack Pattern Name
CAPEC-3	Using Leading 'Ghost' Character Sequences to Bypass Input Filters

Content History

Submissions
Submission Date	Submitter	Organization
2006-07-19 (CWE Draft 3, 2006-07-19)	PLOVER
2006-07-19 (CWE Draft 3, 2006-07-19)
Modifications
Modification Date	Modifier	Organization
2024-02-29 (CWE 4.14, 2024-02-29)	CWE Content Team	MITRE
2024-02-29 (CWE 4.14, 2024-02-29)	updated Observed_Examples
2023-10-26	CWE Content Team	MITRE
2023-10-26	updated Observed_Examples
2023-06-29	CWE Content Team	MITRE
2023-06-29	updated Mapping_Notes
2023-04-27	CWE Content Team	MITRE
2023-04-27	updated Relationships
2023-01-31	CWE Content Team	MITRE
2023-01-31	updated Description
2020-06-25	CWE Content Team	MITRE
2020-06-25	updated Observed_Examples, Potential_Mitigations, Relationships
2020-02-24	CWE Content Team	MITRE
2020-02-24	updated Potential_Mitigations, Relationships
2019-06-20	CWE Content Team	MITRE
2019-06-20	updated Related_Attack_Patterns
2017-11-08	CWE Content Team	MITRE
2017-11-08	updated Affected_Resources, Applicable_Platforms, Relationships, Taxonomy_Mappings
2014-07-30	CWE Content Team	MITRE
2014-07-30	updated Detection_Factors, Relationships
2012-10-30	CWE Content Team	MITRE
2012-10-30	updated Potential_Mitigations
2012-05-11	CWE Content Team	MITRE
2012-05-11	updated Common_Consequences, Observed_Examples, Relationships
2011-09-13	CWE Content Team	MITRE
2011-09-13	updated Relationships, Taxonomy_Mappings
2011-06-01	CWE Content Team	MITRE
2011-06-01	updated Common_Consequences
2011-03-29	CWE Content Team	MITRE
2011-03-29	updated Other_Notes, Potential_Mitigations, Relationship_Notes
2009-07-27	CWE Content Team	MITRE
2009-07-27	updated Potential_Mitigations
2009-05-27	CWE Content Team	MITRE
2009-05-27	updated Name
2009-03-10	CWE Content Team	MITRE
2009-03-10	updated Relationships
2008-11-24	CWE Content Team	MITRE
2008-11-24	updated Relationships, Taxonomy_Mappings
2008-10-14	CWE Content Team	MITRE
2008-10-14	updated Description
2008-09-08	CWE Content Team	MITRE
2008-09-08	updated Relationships, Other_Notes, Taxonomy_Mappings, Type
2008-07-01	Eric Dalci	Cigital
2008-07-01	updated Potential_Mitigations, Time_of_Introduction
Previous Entry Names
Change Date	Previous Entry Name
2008-04-11	Path Equivalence
2009-05-27	Failure to Resolve Path Equivalence

Weakness ID: 404

Vulnerability Mapping: ALLOWED This CWE ID could be used to map to real-world vulnerabilities in limited situations requiring careful review (with careful review of mapping notes)
Abstraction: Class Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.

View customized information:

Description

The product does not release or incorrectly releases a resource before it is made available for re-use.

Extended Description

When a resource is created or allocated, the developer is responsible for properly releasing the resource as well as accounting for all potential paths of expiration or invalidation, such as a set period of time or revocation.

Common Consequences

Impact	Details
DoS: Resource Consumption (Other); Varies by Context	Scope: Availability, Other Most unreleased resource issues result in general software reliability problems, but if an attacker can intentionally trigger a resource leak, the attacker might be able to launch a denial of service attack by depleting the resource pool.
Read Application Data	Scope: Confidentiality When a resource containing sensitive information is not correctly shutdown, it may expose the sensitive data in a subsequent allocation.

Potential Mitigations

Phase(s)	Mitigation
Requirements	Strategy: Language Selection Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, languages such as Java, Ruby, and Lisp perform automatic garbage collection that releases memory for objects that have been deallocated.
Implementation	It is good practice to be responsible for freeing all resources you allocate and to be consistent with how and where you free memory in a function. If you allocate memory that you intend to free upon completion of the function, you must be sure to free the memory at all exit points for that function including error conditions.
Implementation	Memory should be allocated/freed using matching functions such as malloc/free, new/delete, and new[]/delete[].
Implementation	When releasing a complex object or structure, ensure that you properly dispose of all of its member components, not just the object itself.

Relationships

Relevant to the view "Research Concepts" (View-1000)

Nature	Type	ID	Name
ChildOf	Pillar - a weakness that is the most abstract type of weakness and represents a theme for all class/base/variant weaknesses related to it. A Pillar is different from a Category as a Pillar is still technically a type of weakness that describes a mistake, while a Category represents a common characteristic used to group related things.	664	Improper Control of a Resource Through its Lifetime
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	299	Improper Check for Certificate Revocation
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	459	Incomplete Cleanup
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	763	Release of Invalid Pointer or Reference
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	772	Missing Release of Resource after Effective Lifetime
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	1266	Improper Scrubbing of Sensitive Data from Decommissioned Device
PeerOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	239	Failure to Handle Incomplete Element
PeerOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	405	Asymmetric Resource Consumption (Amplification)
CanPrecede	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	619	Dangling Database Cursor ('Cursor Injection')

Relevant to the view "Weaknesses for Simplified Mapping of Published Vulnerabilities" (View-1003)

Nature	Type	ID	Name
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1003	Weaknesses for Simplified Mapping of Published Vulnerabilities
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	401	Missing Release of Memory after Effective Lifetime
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	459	Incomplete Cleanup
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	763	Release of Invalid Pointer or Reference
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	772	Missing Release of Resource after Effective Lifetime

Relevant to the view "CISQ Quality Measures (2020)" (View-1305)

Nature	Type	ID	Name
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	401	Missing Release of Memory after Effective Lifetime
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	772	Missing Release of Resource after Effective Lifetime
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	775	Missing Release of File Descriptor or Handle after Effective Lifetime

Relevant to the view "CISQ Data Protection Measures" (View-1340)

Nature	Type	ID	Name
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	761	Free of Pointer not at Start of Buffer
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	762	Mismatched Memory Management Routines
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	763	Release of Invalid Pointer or Reference
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	772	Missing Release of Resource after Effective Lifetime
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	775	Missing Release of File Descriptor or Handle after Effective Lifetime

Modes Of Introduction

Phase	Note
Implementation

Applicable Platforms

Languages

Class: Not Language-Specific (Undetermined Prevalence)

Likelihood Of Exploit

Medium

Demonstrative Examples

Example 1

The following method never closes the new file handle. Given enough time, the Finalize() method for BufferReader should eventually call Close(), but there is no guarantee as to how long this action will take. In fact, there is no guarantee that Finalize() will ever be invoked. In a busy environment, the Operating System could use up all of the available file handles before the Close() function is called.

(bad code)

Example Language: Java

private void processFile(string fName)
{

BufferReader fil = new BufferReader(new FileReader(fName));
String line;
while ((line = fil.ReadLine()) != null)
{

processLine(line);

}

The good code example simply adds an explicit call to the Close() function when the system is done using the file. Within a simple example such as this the problem is easy to see and fix. In a real system, the problem may be considerably more obscure.

(good code)

Example Language: Java

private void processFile(string fName)
{

BufferReader fil = new BufferReader(new FileReader(fName));
String line;
while ((line = fil.ReadLine()) != null)
{

processLine(line);

}
fil.Close();

}

Example 2

This code attempts to open a connection to a database and catches any exceptions that may occur.

(bad code)

Example Language: Java

try {

Connection con = DriverManager.getConnection(some_connection_string);

}
catch ( Exception e ) {

log( e );

}

If an exception occurs after establishing the database connection and before the same connection closes, the pool of database connections may become exhausted. If the number of available connections is exceeded, other users cannot access this resource, effectively denying access to the application.

Example 3

Under normal conditions the following C# code executes a database query, processes the results returned by the database, and closes the allocated SqlConnection object. But if an exception occurs while executing the SQL or processing the results, the SqlConnection object is not closed. If this happens often enough, the database will run out of available cursors and not be able to execute any more SQL queries.

(bad code)

Example Language: C#

...
SqlConnection conn = new SqlConnection(connString);
SqlCommand cmd = new SqlCommand(queryString);
cmd.Connection = conn;
conn.Open();
SqlDataReader rdr = cmd.ExecuteReader();
HarvestResults(rdr);
conn.Connection.Close();
...

Example 4

The following C function does not close the file handle it opens if an error occurs. If the process is long-lived, the process can run out of file handles.

(bad code)

Example Language: C

int decodeFile(char* fName) {

char buf[BUF_SZ];
FILE* f = fopen(fName, "r");
if (!f) {

printf("cannot open %s\n", fName);
return DECODE_FAIL;

}
else {

while (fgets(buf, BUF_SZ, f)) {

if (!checkChecksum(buf)) {

return DECODE_FAIL;

}
else {

decodeBlock(buf);

}

}
fclose(f);
return DECODE_SUCCESS;

}

Example 5

In this example, the program does not use matching functions such as malloc/free, new/delete, and new[]/delete[] to allocate/deallocate the resource.

(bad code)

Example Language: C++

class A {

void foo();

};
void A::foo(){

int *ptr;
ptr = (int*)malloc(sizeof(int));
delete ptr;

}

Example 6

In this example, the program calls the delete[] function on non-heap memory.

(bad code)

Example Language: C++

class A{

void foo(bool);

};
void A::foo(bool heap) {

int localArray[2] = {

11,22

};
int *p = localArray;
if (heap){

p = new int[2];

}
delete[] p;

}

Selected Observed Examples

Reference	Description
CVE-1999-1127	Does not shut down named pipe connections if malformed data is sent.
CVE-2001-0830	Sockets not properly closed when attacker repeatedly connects and disconnects from server.
CVE-2002-1372	Chain: Return values of file/socket operations are not checked (CWE-252), allowing resultant consumption of file descriptors (CWE-772).

Weakness Ordinalities

Ordinality	Description
Primary	(where the weakness exists independent of other weaknesses) Improper release or shutdown of resources can be primary to resource exhaustion, performance, and information confidentiality problems to name a few.
Resultant	(where the weakness is typically related to the presence of some other weaknesses) Improper release or shutdown of resources can be resultant from improper error handling or insufficient resource tracking.

Detection Methods

Method	Details
Automated Dynamic Analysis	This weakness can be detected using dynamic tools and techniques that interact with the software using large test suites with many diverse inputs, such as fuzz testing (fuzzing), robustness testing, and fault injection. The software's operation may slow down, but it should not become unstable, crash, or generate incorrect results. Resource clean up errors might be detected with a stress-test by calling the software simultaneously from a large number of threads or processes, and look for evidence of any unexpected behavior. The software's operation may slow down, but it should not become unstable, crash, or generate incorrect results. Effectiveness: Moderate
Manual Dynamic Analysis	Identify error conditions that are not likely to occur during normal usage and trigger them. For example, run the product under low memory conditions, run with insufficient privileges or permissions, interrupt a transaction before it is completed, or disable connectivity to basic network services such as DNS. Monitor the software for any unexpected behavior. If you trigger an unhandled exception or similar error that was discovered and handled by the application's environment, it may still indicate unexpected conditions that were not handled by the application itself.
Automated Static Analysis	Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.) Effectiveness: High

Memberships

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	398	7PK - Code Quality
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	730	OWASP Top Ten 2004 Category A9 - Denial of Service
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	743	CERT C Secure Coding Standard (2008) Chapter 10 - Input Output (FIO)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	752	2009 Top 25 - Risky Resource Management
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	857	The CERT Oracle Secure Coding Standard for Java (2011) Chapter 14 - Input Output (FIO)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	876	CERT C++ Secure Coding Section 08 - Memory Management (MEM)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	877	CERT C++ Secure Coding Section 09 - Input Output (FIO)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	882	CERT C++ Secure Coding Section 14 - Concurrency (CON)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	982	SFP Secondary Cluster: Failure to Release Resource
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1147	SEI CERT Oracle Secure Coding Standard for Java - Guidelines 13. Input Output (FIO)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1162	SEI CERT C Coding Standard - Guidelines 08. Memory Management (MEM)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1163	SEI CERT C Coding Standard - Guidelines 09. Input Output (FIO)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1306	CISQ Quality Measures - Reliability
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1308	CISQ Quality Measures - Security
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1309	CISQ Quality Measures - Efficiency
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1340	CISQ Data Protection Measures
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1416	Comprehensive Categorization: Resource Lifecycle Management

Vulnerability Mapping Notes

Usage	ALLOWED-WITH-REVIEW (this CWE ID could be used to map to real-world vulnerabilities in limited situations requiring careful review)
Reason	Abstraction
Rationale	This CWE entry is a Class and might have Base-level children that would be more appropriate
Comments	Examine children of this entry to see if there is a better fit

Notes

Relationship

Overlaps memory leaks, asymmetric resource consumption, malformed input errors.

Taxonomy Mappings

Mapped Taxonomy Name	Node ID	Fit	Mapped Node Name
PLOVER			Improper resource shutdown or release
7 Pernicious Kingdoms			Unreleased Resource
OWASP Top Ten 2004	A9	CWE More Specific	Denial of Service
CERT C Secure Coding	FIO42-C	CWE More Abstract	Close files when they are no longer needed
CERT C Secure Coding	MEM31-C	CWE More Abstract	Free dynamically allocated memory when no longer needed
The CERT Oracle Secure Coding Standard for Java (2011)	FIO04-J		Release resources when they are no longer needed
Software Fault Patterns	SFP14		Failure to release resource

Related Attack Patterns

CAPEC-ID	Attack Pattern Name
CAPEC-125	Flooding
CAPEC-130	Excessive Allocation
CAPEC-131	Resource Leak Exposure
CAPEC-494	TCP Fragmentation
CAPEC-495	UDP Fragmentation
CAPEC-496	ICMP Fragmentation
CAPEC-666	BlueSmacking

References

[REF-44]

Michael Howard, David LeBlanc and John Viega. "24 Deadly Sins of Software Security". "Sin 8: C++ Catastrophes." Page 143. McGraw-Hill. 2010.

Content History

Submissions
Submission Date	Submitter	Organization
2006-07-19 (CWE Draft 3, 2006-07-19)	PLOVER
2006-07-19 (CWE Draft 3, 2006-07-19)
Modifications
Modification Date	Modifier	Organization
2023-10-26	CWE Content Team	MITRE
2023-10-26	updated Observed_Examples
2023-06-29	CWE Content Team	MITRE
2023-06-29	updated Mapping_Notes
2023-04-27	CWE Content Team	MITRE
2023-04-27	updated Detection_Factors, Relationships, Time_of_Introduction
2023-01-31	CWE Content Team	MITRE
2023-01-31	updated Description, Detection_Factors
2022-10-13	CWE Content Team	MITRE
2022-10-13	updated Relationships
2021-07-20	CWE Content Team	MITRE
2021-07-20	updated Related_Attack_Patterns
2021-03-15	CWE Content Team	MITRE
2021-03-15	updated Demonstrative_Examples
2020-12-10	CWE Content Team	MITRE
2020-12-10	updated Relationships
2020-08-20	CWE Content Team	MITRE
2020-08-20	updated Relationships
2020-06-25	CWE Content Team	MITRE
2020-06-25	updated Relationships
2020-02-24	CWE Content Team	MITRE
2020-02-24	updated Relationships
2019-06-20	CWE Content Team	MITRE
2019-06-20	updated Related_Attack_Patterns, Relationships
2019-01-03	CWE Content Team	MITRE
2019-01-03	updated Relationships, Taxonomy_Mappings, Type
2017-11-08	CWE Content Team	MITRE
2017-11-08	updated Applicable_Platforms, Functional_Areas, Likelihood_of_Exploit, Relationships, Taxonomy_Mappings
2017-05-03	CWE Content Team	MITRE
2017-05-03	updated Related_Attack_Patterns
2017-01-19	CWE Content Team	MITRE
2017-01-19	updated Relationships
2015-12-07	CWE Content Team	MITRE
2015-12-07	updated Relationships
2014-07-30	CWE Content Team	MITRE
2014-07-30	updated Relationships, Taxonomy_Mappings
2014-06-23	CWE Content Team	MITRE
2014-06-23	updated Related_Attack_Patterns
2014-02-18	CWE Content Team	MITRE
2014-02-18	updated Demonstrative_Examples
2012-05-11	CWE Content Team	MITRE
2012-05-11	updated Demonstrative_Examples, References, Relationships, Taxonomy_Mappings
2011-09-13	CWE Content Team	MITRE
2011-09-13	updated Relationships, Taxonomy_Mappings
2011-06-27	CWE Content Team	MITRE
2011-06-27	updated Common_Consequences
2011-06-01	CWE Content Team	MITRE
2011-06-01	updated Common_Consequences, Relationships, Taxonomy_Mappings
2011-03-29	CWE Content Team	MITRE
2011-03-29	updated Weakness_Ordinalities
2010-12-13	CWE Content Team	MITRE
2010-12-13	updated Demonstrative_Examples
2010-06-21	CWE Content Team	MITRE
2010-06-21	updated Detection_Factors, Potential_Mitigations
2010-02-16	CWE Content Team	MITRE
2010-02-16	updated Potential_Mitigations, Relationships
2009-10-29	CWE Content Team	MITRE
2009-10-29	updated Other_Notes
2009-07-27	CWE Content Team	MITRE
2009-07-27	updated Demonstrative_Examples, Related_Attack_Patterns
2009-05-27	CWE Content Team	MITRE
2009-05-27	updated Description, Relationships
2009-03-10	CWE Content Team	MITRE
2009-03-10	updated Potential_Mitigations
2009-01-12	CWE Content Team	MITRE
2009-01-12	updated Common_Consequences, Likelihood_of_Exploit, Other_Notes, Potential_Mitigations, Relationship_Notes, Relationships, Weakness_Ordinalities
2008-11-24	CWE Content Team	MITRE
2008-11-24	updated Relationships, Taxonomy_Mappings
2008-10-14	CWE Content Team	MITRE
2008-10-14	updated Relationships
2008-09-08	CWE Content Team	MITRE
2008-09-08	updated Description, Relationships, Other_Notes, Taxonomy_Mappings
2008-08-15		Veracode
2008-08-15	Suggested OWASP Top Ten 2004 mapping
2008-07-01	Eric Dalci	Cigital
2008-07-01	updated Time_of_Introduction

Weakness ID: 119

View customized information:

Description

Alternate Terms

Buffer Overflow	This term has many different meanings to different audiences. From a CWE mapping perspective, this term should be avoided where possible. Some researchers, developers, and tools intend for it to mean "write past the end of a buffer," whereas others use the same term to mean "any read or write outside the boundaries of a buffer, whether before the beginning of the buffer or after the end of the buffer." Others could mean "any action after the end of a buffer, whether it is a read or write." Since the term is commonly used for exploitation and for vulnerabilities, it further confuses things.
buffer overrun	Some prominent vendors and researchers use the term "buffer overrun," but most people use "buffer overflow." See the alternate term for "buffer overflow" for context.
memory safety	Generally used for techniques that avoid weaknesses related to memory access, such as those identified by CWE-119 and its descendants. However, the term is not formal, and there is likely disagreement between practitioners as to which weaknesses are implicitly covered by the "memory safety" term.

Common Consequences

Impact	Details
Execute Unauthorized Code or Commands; Modify Memory	Scope: Integrity, Confidentiality, Availability If the memory accessible by the attacker can be effectively controlled, it may be possible to execute arbitrary code, as with a standard buffer overflow. If the attacker can overwrite a pointer's worth of memory (usually 32 or 64 bits), they can alter the intended control flow by redirecting a function pointer to their own malicious code. Even when the attacker can only modify a single byte arbitrary code execution can be possible. Sometimes this is because the same problem can be exploited repeatedly to the same effect. Other times it is because the attacker can overwrite security-critical application-specific data -- such as a flag indicating whether the user is an administrator.
Read Memory; DoS: Crash, Exit, or Restart; DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory)	Scope: Availability, Confidentiality Out of bounds memory access will very likely result in the corruption of relevant memory, and perhaps instructions, possibly leading to a crash. Other attacks leading to lack of availability are possible, including putting the program into an infinite loop.
Read Memory	Scope: Confidentiality In the case of an out-of-bounds read, the attacker may have access to sensitive information. If the sensitive information contains system details, such as the current buffer's position in memory, this knowledge can be used to craft further attacks, possibly with more severe consequences.

Potential Mitigations

Phase(s)	Mitigation
Requirements	Strategy: Language Selection Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, many languages that perform their own memory management, such as Java and Perl, are not subject to buffer overflows. Other languages, such as Ada and C#, typically provide overflow protection, but the protection can be disabled by the programmer. Be wary that a language's interface to native code may still be subject to overflows, even if the language itself is theoretically safe.
Architecture and Design	Strategy: Libraries or Frameworks Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. Examples include the Safe C String Library (SafeStr) by Messier and Viega [REF-57], and the Strsafe.h library from Microsoft [REF-56]. These libraries provide safer versions of overflow-prone string-handling functions. Note: This is not a complete solution, since many buffer overflows are not related to strings.
Operation; Build and Compilation	Strategy: Environment Hardening Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index checking. D3-SFCV (Stack Frame Canary Validation) from D3FEND [REF-1334] discusses canary-based detection in detail. Effectiveness: Defense in Depth Note: This is not necessarily a complete solution, since these mechanisms only detect certain types of overflows. In addition, the result is still a denial of service, since the typical response is to exit the application.
Implementation	Consider adhering to the following rules when allocating and managing an application's memory: Double check that the buffer is as large as specified. When using functions that accept a number of bytes to copy, such as strncpy(), be aware that if the destination buffer size is equal to the source buffer size, it may not NULL-terminate the string. Check buffer boundaries if accessing the buffer in a loop and make sure there is no danger of writing past the allocated space. If necessary, truncate all input strings to a reasonable length before passing them to the copy and concatenation functions.
Operation; Build and Compilation	Strategy: Environment Hardening Run or compile the software using features or extensions that randomly arrange the positions of a program's executable and libraries in memory. Because this makes the addresses unpredictable, it can prevent an attacker from reliably jumping to exploitable code. Examples include Address Space Layout Randomization (ASLR) [REF-58] [REF-60] and Position-Independent Executables (PIE) [REF-64]. Imported modules may be similarly realigned if their default memory addresses conflict with other modules, in a process known as "rebasing" (for Windows) and "prelinking" (for Linux) [REF-1332] using randomly generated addresses. ASLR for libraries cannot be used in conjunction with prelink since it would require relocating the libraries at run-time, defeating the whole purpose of prelinking. For more information on these techniques see D3-SAOR (Segment Address Offset Randomization) from D3FEND [REF-1335]. Effectiveness: Defense in Depth Note: These techniques do not provide a complete solution. For instance, exploits frequently use a bug that discloses memory addresses in order to maximize reliability of code execution [REF-1337]. It has also been shown that a side-channel attack can bypass ASLR [REF-1333]
Operation	Strategy: Environment Hardening Use a CPU and operating system that offers Data Execution Protection (using hardware NX or XD bits) or the equivalent techniques that simulate this feature in software, such as PaX [REF-60] [REF-61]. These techniques ensure that any instruction executed is exclusively at a memory address that is part of the code segment. For more information on these techniques see D3-PSEP (Process Segment Execution Prevention) from D3FEND [REF-1336]. Effectiveness: Defense in Depth Note: This is not a complete solution, since buffer overflows could be used to overwrite nearby variables to modify the software's state in dangerous ways. In addition, it cannot be used in cases in which self-modifying code is required. Finally, an attack could still cause a denial of service, since the typical response is to exit the application.
Implementation	Replace unbounded copy functions with analogous functions that support length arguments, such as strcpy with strncpy. Create these if they are not available. Effectiveness: Moderate Note: This approach is still susceptible to calculation errors, including issues such as off-by-one errors (CWE-193) and incorrectly calculating buffer lengths (CWE-131).

Relationships

Relevant to the view "Research Concepts" (View-1000)

Nature	Type	ID	Name
ChildOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	118	Incorrect Access of Indexable Resource ('Range Error')
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	125	Out-of-bounds Read
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	466	Return of Pointer Value Outside of Expected Range
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	786	Access of Memory Location Before Start of Buffer
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	787	Out-of-bounds Write
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	788	Access of Memory Location After End of Buffer
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	805	Buffer Access with Incorrect Length Value
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	822	Untrusted Pointer Dereference
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	823	Use of Out-of-range Pointer Offset
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	824	Access of Uninitialized Pointer
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	825	Expired Pointer Dereference
CanFollow	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	20	Improper Input Validation
CanFollow	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	128	Wrap-around Error
CanFollow	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	129	Improper Validation of Array Index
CanFollow	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	131	Incorrect Calculation of Buffer Size
CanFollow	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	190	Integer Overflow or Wraparound
CanFollow	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	193	Off-by-one Error
CanFollow	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	195	Signed to Unsigned Conversion Error
CanFollow	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	839	Numeric Range Comparison Without Minimum Check
CanFollow	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	843	Access of Resource Using Incompatible Type ('Type Confusion')
CanFollow	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	1257	Improper Access Control Applied to Mirrored or Aliased Memory Regions
CanFollow	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	1260	Improper Handling of Overlap Between Protected Memory Ranges
CanFollow	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	1339	Insufficient Precision or Accuracy of a Real Number

Relevant to the view "Weaknesses for Simplified Mapping of Published Vulnerabilities" (View-1003)

Nature	Type	ID	Name
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1003	Weaknesses for Simplified Mapping of Published Vulnerabilities
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	120	Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	125	Out-of-bounds Read
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	787	Out-of-bounds Write
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	824	Access of Uninitialized Pointer

Relevant to the view "CISQ Quality Measures (2020)" (View-1305)

Nature	Type	ID	Name
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	125	Out-of-bounds Read
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	130	Improper Handling of Length Parameter Inconsistency
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	786	Access of Memory Location Before Start of Buffer
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	787	Out-of-bounds Write
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	788	Access of Memory Location After End of Buffer
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	805	Buffer Access with Incorrect Length Value
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	822	Untrusted Pointer Dereference
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	823	Use of Out-of-range Pointer Offset
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	824	Access of Uninitialized Pointer
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	825	Expired Pointer Dereference

Relevant to the view "CISQ Data Protection Measures" (View-1340)

Nature	Type	ID	Name
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	123	Write-what-where Condition
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	125	Out-of-bounds Read
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	130	Improper Handling of Length Parameter Inconsistency
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	786	Access of Memory Location Before Start of Buffer
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	787	Out-of-bounds Write
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	788	Access of Memory Location After End of Buffer
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	805	Buffer Access with Incorrect Length Value
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	822	Untrusted Pointer Dereference
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	823	Use of Out-of-range Pointer Offset
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	824	Access of Uninitialized Pointer
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	825	Expired Pointer Dereference

Relevant to the view "Seven Pernicious Kingdoms" (View-700)

Nature	Type	ID	Name
ChildOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	20	Improper Input Validation

Background Details

Certain languages allow direct addressing of memory locations and do not automatically ensure that these locations are valid for the memory buffer that is being referenced.

Modes Of Introduction

Phase	Note
Implementation

Applicable Platforms

Languages

C (Often Prevalent)

C++ (Often Prevalent)

Class: Assembly (Undetermined Prevalence)

Likelihood Of Exploit

High

Demonstrative Examples

Example 1

This example takes an IP address from a user, verifies that it is well formed and then looks up the hostname and copies it into a buffer.

(bad code)

Example Language: C

void host_lookup(char *user_supplied_addr){

}

This function allocates a buffer of 64 bytes to store the hostname, however there is no guarantee that the hostname will not be larger than 64 bytes. If an attacker specifies an address which resolves to a very large hostname, then the function may overwrite sensitive data or even relinquish control flow to the attacker.

Note that this example also contains an unchecked return value (CWE-252) that can lead to a NULL pointer dereference (CWE-476).

Example 2

This example applies an encoding procedure to an input string and stores it into a buffer.

(bad code)

Example Language: C

char * copy_input(char *user_supplied_string){

int i, dst_index;
char *dst_buf = (char*)malloc(4*sizeof(char) * MAX_SIZE);
if ( MAX_SIZE <= strlen(user_supplied_string) ){

die("user string too long, die evil hacker!");

}
dst_index = 0;
for ( i = 0; i < strlen(user_supplied_string); i++ ){

if( '&' == user_supplied_string[i] ){

dst_buf[dst_index++] = '&';
dst_buf[dst_index++] = 'a';
dst_buf[dst_index++] = 'm';
dst_buf[dst_index++] = 'p';
dst_buf[dst_index++] = ';';

}
else if ('<' == user_supplied_string[i] ){

/* encode to < */

}
else dst_buf[dst_index++] = user_supplied_string[i];

}
return dst_buf;

}

The programmer attempts to encode the ampersand character in the user-controlled string, however the length of the string is validated before the encoding procedure is applied. Furthermore, the programmer assumes encoding expansion will only expand a given character by a factor of 4, while the encoding of the ampersand expands by 5. As a result, when the encoding procedure expands the string it is possible to overflow the destination buffer if the attacker provides a string of many ampersands.

Example 3

The following example asks a user for an offset into an array to select an item.

(bad code)

Example Language: C

int main (int argc, char **argv) {

char *items[] = {"boat", "car", "truck", "train"};
int index = GetUntrustedOffset();
printf("You selected %s\n", items[index-1]);

}

The programmer allows the user to specify which element in the list to select, however an attacker can provide an out-of-bounds offset, resulting in a buffer over-read (CWE-126).

Example 4

In the following code, the method retrieves a value from an array at a specific array index location that is given as an input parameter to the method

(bad code)

Example Language: C

int getValueFromArray(int *array, int len, int index) {

int value;

// check that the array index is less than the maximum

// length of the array
if (index < len) {

// get the value at the specified index of the array
value = array[index];

}
// if array index is invalid then output error message
// and return value indicating error
else {

printf("Value is: %d\n", array[index]);
value = -1;

}

return value;

}

However, this method only verifies that the given array index is less than the maximum length of the array but does not check for the minimum value (CWE-839). This will allow a negative value to be accepted as the input array index, which will result in a out of bounds read (CWE-125) and may allow access to sensitive memory. The input array index should be checked to verify that is within the maximum and minimum range required for the array (CWE-129). In this example the if statement should be modified to include a minimum range check, as shown below.

(good code)

Example Language: C

...

// check that the array index is within the correct

// range of values for the array
if (index >= 0 && index < len) {

...

Example 5

Windows provides the _mbs family of functions to perform various operations on multibyte strings. When these functions are passed a malformed multibyte string, such as a string containing a valid leading byte followed by a single null byte, they can read or write past the end of the string buffer causing a buffer overflow. The following functions all pose a risk of buffer overflow: _mbsinc _mbsdec _mbsncat _mbsncpy _mbsnextc _mbsnset _mbsrev _mbsset _mbsstr _mbstok _mbccpy _mbslen

Selected Observed Examples

Reference	Description
CVE-2021-22991	Incorrect URI normalization in application traffic product leads to buffer overflow, as exploited in the wild per CISA KEV.
CVE-2020-29557	Buffer overflow in Wi-Fi router web interface, as exploited in the wild per CISA KEV.
CVE-2009-2550	Classic stack-based buffer overflow in media player using a long entry in a playlist
CVE-2009-2403	Heap-based buffer overflow in media player using a long entry in a playlist
CVE-2009-0689	large precision value in a format string triggers overflow
CVE-2009-0690	negative offset value leads to out-of-bounds read
CVE-2009-1532	malformed inputs cause accesses of uninitialized or previously-deleted objects, leading to memory corruption
CVE-2009-1528	chain: lack of synchronization leads to memory corruption
CVE-2021-29529	Chain: machine-learning product can have a heap-based buffer overflow (CWE-122) when some integer-oriented bounds are calculated by using ceiling() and floor() on floating point values (CWE-1339)
CVE-2009-0558	attacker-controlled array index leads to code execution
CVE-2009-0269	chain: -1 value from a function call was intended to indicate an error, but is used as an array index instead.
CVE-2009-0566	chain: incorrect calculations lead to incorrect pointer dereference and memory corruption
CVE-2009-1350	product accepts crafted messages that lead to a dereference of an arbitrary pointer
CVE-2009-0191	chain: malformed input causes dereference of uninitialized memory
CVE-2008-4113	OS kernel trusts userland-supplied length value, allowing reading of sensitive information
CVE-2005-1513	Chain: integer overflow in securely-coded mail program leads to buffer overflow. In 2005, this was regarded as unrealistic to exploit, but in 2020, it was rediscovered to be easier to exploit due to evolutions of the technology.
CVE-2003-0542	buffer overflow involving a regular expression with a large number of captures
CVE-2017-1000121	chain: unchecked message size metadata allows integer overflow (CWE-190) leading to buffer overflow (CWE-119).

Detection Methods

Method	Details
Automated Static Analysis	This weakness can often be detected using automated static analysis tools. Many modern tools use data flow analysis or constraint-based techniques to minimize the number of false positives. Automated static analysis generally does not account for environmental considerations when reporting out-of-bounds memory operations. This can make it difficult for users to determine which warnings should be investigated first. For example, an analysis tool might report buffer overflows that originate from command line arguments in a program that is not expected to run with setuid or other special privileges. Effectiveness: High Note:Detection techniques for buffer-related errors are more mature than for most other weakness types.
Automated Dynamic Analysis	This weakness can be detected using dynamic tools and techniques that interact with the software using large test suites with many diverse inputs, such as fuzz testing (fuzzing), robustness testing, and fault injection. The software's operation may slow down, but it should not become unstable, crash, or generate incorrect results.
Automated Static Analysis - Binary or Bytecode	According to SOAR, the following detection techniques may be useful: Cost effective for partial coverage: Binary / Bytecode Quality Analysis Bytecode Weakness Analysis - including disassembler + source code weakness analysis Binary Weakness Analysis - including disassembler + source code weakness analysis Effectiveness: SOAR Partial
Manual Static Analysis - Binary or Bytecode	According to SOAR, the following detection techniques may be useful: Cost effective for partial coverage: Binary / Bytecode disassembler - then use manual analysis for vulnerabilities & anomalies Effectiveness: SOAR Partial
Dynamic Analysis with Automated Results Interpretation	According to SOAR, the following detection techniques may be useful: Cost effective for partial coverage: Web Application Scanner Web Services Scanner Database Scanners Effectiveness: SOAR Partial
Dynamic Analysis with Manual Results Interpretation	According to SOAR, the following detection techniques may be useful: Cost effective for partial coverage: Fuzz Tester Framework-based Fuzzer Effectiveness: SOAR Partial
Manual Static Analysis - Source Code	According to SOAR, the following detection techniques may be useful: Cost effective for partial coverage: Focused Manual Spotcheck - Focused manual analysis of source Manual Source Code Review (not inspections) Effectiveness: SOAR Partial
Automated Static Analysis - Source Code	According to SOAR, the following detection techniques may be useful: Highly cost effective: Source code Weakness Analyzer Context-configured Source Code Weakness Analyzer Cost effective for partial coverage: Source Code Quality Analyzer Effectiveness: High
Architecture or Design Review	According to SOAR, the following detection techniques may be useful: Highly cost effective: Formal Methods / Correct-By-Construction Cost effective for partial coverage: Inspection (IEEE 1028 standard) (can apply to requirements, design, source code, etc.) Effectiveness: High

Affected Resources

Memory

Memberships

Nature	Type	ID	Name
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	635	Weaknesses Originally Used by NVD from 2008 to 2016
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	726	OWASP Top Ten 2004 Category A5 - Buffer Overflows
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	740	CERT C Secure Coding Standard (2008) Chapter 7 - Arrays (ARR)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	741	CERT C Secure Coding Standard (2008) Chapter 8 - Characters and Strings (STR)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	742	CERT C Secure Coding Standard (2008) Chapter 9 - Memory Management (MEM)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	743	CERT C Secure Coding Standard (2008) Chapter 10 - Input Output (FIO)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	744	CERT C Secure Coding Standard (2008) Chapter 11 - Environment (ENV)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	752	2009 Top 25 - Risky Resource Management
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	874	CERT C++ Secure Coding Section 06 - Arrays and the STL (ARR)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	875	CERT C++ Secure Coding Section 07 - Characters and Strings (STR)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	876	CERT C++ Secure Coding Section 08 - Memory Management (MEM)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	877	CERT C++ Secure Coding Section 09 - Input Output (FIO)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	878	CERT C++ Secure Coding Section 10 - Environment (ENV)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	970	SFP Secondary Cluster: Faulty Buffer Access
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1157	SEI CERT C Coding Standard - Guidelines 03. Expressions (EXP)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1160	SEI CERT C Coding Standard - Guidelines 06. Arrays (ARR)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1161	SEI CERT C Coding Standard - Guidelines 07. Characters and Strings (STR)
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1200	Weaknesses in the 2019 CWE Top 25 Most Dangerous Software Errors
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1306	CISQ Quality Measures - Reliability
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1308	CISQ Quality Measures - Security
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1337	Weaknesses in the 2021 CWE Top 25 Most Dangerous Software Weaknesses
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1340	CISQ Data Protection Measures
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1350	Weaknesses in the 2020 CWE Top 25 Most Dangerous Software Weaknesses
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1387	Weaknesses in the 2022 CWE Top 25 Most Dangerous Software Weaknesses
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1399	Comprehensive Categorization: Memory Safety
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1425	Weaknesses in the 2023 CWE Top 25 Most Dangerous Software Weaknesses
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1430	Weaknesses in the 2024 CWE Top 25 Most Dangerous Software Weaknesses

Vulnerability Mapping Notes

Usage	DISCOURAGED (this CWE ID should not be used to map to real-world vulnerabilities)
Reason	Frequent Misuse
Rationale	CWE-119 is commonly misused in low-information vulnerability reports when lower-level CWEs could be used instead, or when more details about the vulnerability are available.
Comments	Look at CWE-119's children and consider mapping to CWEs such as CWE-787: Out-of-bounds Write, CWE-125: Out-of-bounds Read, or others.

Notes

Applicable Platform

It is possible in any programming languages without memory management support to attempt an operation outside of the bounds of a memory buffer, but the consequences will vary widely depending on the language, platform, and chip architecture.

Taxonomy Mappings

Mapped Taxonomy Name	Node ID	Fit	Mapped Node Name
OWASP Top Ten 2004	A5	Exact	Buffer Overflows
CERT C Secure Coding	ARR00-C		Understand how arrays work
CERT C Secure Coding	ARR30-C	CWE More Abstract	Do not form or use out-of-bounds pointers or array subscripts
CERT C Secure Coding	ARR38-C	CWE More Abstract	Guarantee that library functions do not form invalid pointers
CERT C Secure Coding	ENV01-C		Do not make assumptions about the size of an environment variable
CERT C Secure Coding	EXP39-C	Imprecise	Do not access a variable through a pointer of an incompatible type
CERT C Secure Coding	FIO37-C		Do not assume character data has been read
CERT C Secure Coding	STR31-C	CWE More Abstract	Guarantee that storage for strings has sufficient space for character data and the null terminator
CERT C Secure Coding	STR32-C	CWE More Abstract	Do not pass a non-null-terminated character sequence to a library function that expects a string
WASC	7		Buffer Overflow
Software Fault Patterns	SFP8		Faulty Buffer Access

Related Attack Patterns

CAPEC-ID	Attack Pattern Name
CAPEC-10	Buffer Overflow via Environment Variables
CAPEC-100	Overflow Buffers
CAPEC-123	Buffer Manipulation
CAPEC-14	Client-side Injection-induced Buffer Overflow
CAPEC-24	Filter Failure through Buffer Overflow
CAPEC-42	MIME Conversion
CAPEC-44	Overflow Binary Resource File
CAPEC-45	Buffer Overflow via Symbolic Links
CAPEC-46	Overflow Variables and Tags
CAPEC-47	Buffer Overflow via Parameter Expansion
CAPEC-8	Buffer Overflow in an API Call
CAPEC-9	Buffer Overflow in Local Command-Line Utilities

References

[REF-1029]	Aleph One. "Smashing The Stack For Fun And Profit". 1996-11-08. <http://phrack.org/issues/49/14.html>.
[REF-7]	Michael Howard and David LeBlanc. "Writing Secure Code". Chapter 5, "Public Enemy #1: The Buffer Overrun" Page 127; Chapter 14, "Prevent I18N Buffer Overruns" Page 441. 2nd Edition. Microsoft Press. 2002-12-04. <https://www.microsoftpressstore.com/store/writing-secure-code-9780735617223>.
[REF-56]	Microsoft. "Using the Strsafe.h Functions". <https://learn.microsoft.com/en-us/windows/win32/menurc/strsafe-ovw?redirectedfrom=MSDN>. (URL validated: 2023-04-07)
[REF-57]	Matt Messier and John Viega. "Safe C String Library v1.0.3". <http://www.gnu-darwin.org/www001/ports-1.5a-CURRENT/devel/safestr/work/safestr-1.0.3/doc/safestr.html>. (URL validated: 2023-04-07)
[REF-58]	Michael Howard. "Address Space Layout Randomization in Windows Vista". <https://learn.microsoft.com/en-us/archive/blogs/michael_howard/address-space-layout-randomization-in-windows-vista>. (URL validated: 2023-04-07)
[REF-59]	Arjan van de Ven. "Limiting buffer overflows with ExecShield". <https://archive.is/saAFo>. (URL validated: 2023-04-07)
[REF-60]	"PaX". <https://en.wikipedia.org/wiki/Executable_space_protection#PaX>. (URL validated: 2023-04-07)
[REF-61]	Microsoft. "Understanding DEP as a mitigation technology part 1". <https://msrc.microsoft.com/blog/2009/06/understanding-dep-as-a-mitigation-technology-part-1/>. (URL validated: 2023-04-07)
[REF-62]	Mark Dowd, John McDonald and Justin Schuh. "The Art of Software Security Assessment". Chapter 5, "Memory Corruption", Page 167. 1st Edition. Addison Wesley. 2006.
[REF-64]	Grant Murphy. "Position Independent Executables (PIE)". Red Hat. 2012-11-28. <https://www.redhat.com/en/blog/position-independent-executables-pie>. (URL validated: 2023-04-07)
[REF-1332]	John Richard Moser. "Prelink and address space randomization". 2006-07-05. <https://lwn.net/Articles/190139/>. (URL validated: 2023-04-26)
[REF-1333]	Dmitry Evtyushkin, Dmitry Ponomarev, Nael Abu-Ghazaleh. "Jump Over ASLR: Attacking Branch Predictors to Bypass ASLR". 2016. <http://www.cs.ucr.edu/~nael/pubs/micro16.pdf>. (URL validated: 2023-04-26)
[REF-1334]	D3FEND. "Stack Frame Canary Validation (D3-SFCV)". 2023. <https://d3fend.mitre.org/technique/d3f:StackFrameCanaryValidation/>. (URL validated: 2023-04-26)
[REF-1335]	D3FEND. "Segment Address Offset Randomization (D3-SAOR)". 2023. <https://d3fend.mitre.org/technique/d3f:SegmentAddressOffsetRandomization/>. (URL validated: 2023-04-26)
[REF-1336]	D3FEND. "Process Segment Execution Prevention (D3-PSEP)". 2023. <https://d3fend.mitre.org/technique/d3f:ProcessSegmentExecutionPrevention/>. (URL validated: 2023-04-26)
[REF-1337]	Alexander Sotirov and Mark Dowd. "Bypassing Browser Memory Protections: Setting back browser security by 10 years". Memory information leaks. 2008. <https://www.blackhat.com/presentations/bh-usa-08/Sotirov_Dowd/bh08-sotirov-dowd.pdf>. (URL validated: 2023-04-26)

Content History

Submissions
Submission Date	Submitter	Organization
2006-07-19 (CWE Draft 3, 2006-07-19)	PLOVER
2006-07-19 (CWE Draft 3, 2006-07-19)
Contributions
Contribution Date	Contributor	Organization
2024-02-29 (CWE 4.15, 2024-07-16)	Abhi Balakrishnan
2024-02-29 (CWE 4.15, 2024-07-16)	Provided diagram to improve CWE usability
Modifications
Modification Date	Modifier	Organization
2025-04-03 (CWE 4.17, 2025-04-03)	CWE Content Team	MITRE
2025-04-03 (CWE 4.17, 2025-04-03)	updated Relationships
2024-11-19 (CWE 4.16, 2024-11-19)	CWE Content Team	MITRE
2024-11-19 (CWE 4.16, 2024-11-19)	updated Description, Relationships
2024-07-16 (CWE 4.15, 2024-07-16)	CWE Content Team	MITRE
2024-07-16 (CWE 4.15, 2024-07-16)	updated Alternate_Terms, Background_Details, Common_Consequences, Description, Diagram
2023-06-29	CWE Content Team	MITRE
2023-06-29	updated Mapping_Notes, Relationships
2023-04-27	CWE Content Team	MITRE
2023-04-27	updated Potential_Mitigations, References, Relationships, Time_of_Introduction
2023-01-31	CWE Content Team	MITRE
2023-01-31	updated Alternate_Terms, Description
2022-10-13	CWE Content Team	MITRE
2022-10-13	updated Relationships, Taxonomy_Mappings
2022-06-28	CWE Content Team	MITRE
2022-06-28	updated Observed_Examples, Relationships
2021-07-20	CWE Content Team	MITRE
2021-07-20	updated Demonstrative_Examples, Observed_Examples, Potential_Mitigations, Relationships
2020-12-10	CWE Content Team	MITRE
2020-12-10	updated Alternate_Terms, Observed_Examples, Relationships
2020-08-20	CWE Content Team	MITRE
2020-08-20	updated Alternate_Terms, Relationships
2020-06-25	CWE Content Team	MITRE
2020-06-25	updated Relationships
2020-02-24	CWE Content Team	MITRE
2020-02-24	updated Relationships, Taxonomy_Mappings, Time_of_Introduction
2019-09-19	CWE Content Team	MITRE
2019-09-19	updated References, Relationships
2019-06-20	CWE Content Team	MITRE
2019-06-20	updated Related_Attack_Patterns, Relationships
2019-01-03	CWE Content Team	MITRE
2019-01-03	updated Relationships
2018-03-27	CWE Content Team	MITRE
2018-03-27	updated References
2017-11-08	CWE Content Team	MITRE
2017-11-08	updated Applicable_Platforms, Common_Consequences, Demonstrative_Examples, Observed_Examples, References, Relationships, Taxonomy_Mappings
2017-05-03	CWE Content Team	MITRE
2017-05-03	updated Relationships
2017-01-19	CWE Content Team	MITRE
2017-01-19	updated Relationships
2015-12-07	CWE Content Team	MITRE
2015-12-07	updated Relationships
2014-07-30	CWE Content Team	MITRE
2014-07-30	updated Detection_Factors, Relationships, Taxonomy_Mappings
2014-02-18	CWE Content Team	MITRE
2014-02-18	updated Potential_Mitigations, References
2013-02-21	CWE Content Team	MITRE
2013-02-21	updated Demonstrative_Examples
2012-10-30	CWE Content Team	MITRE
2012-10-30	updated Potential_Mitigations
2012-05-11	CWE Content Team	MITRE
2012-05-11	updated Demonstrative_Examples, Potential_Mitigations, References, Relationships
2011-09-13	CWE Content Team	MITRE
2011-09-13	updated Relationships, Taxonomy_Mappings
2011-06-01	CWE Content Team	MITRE
2011-06-01	updated Common_Consequences, Relationships
2011-03-29	CWE Content Team	MITRE
2011-03-29	updated Relationships
2010-12-13	CWE Content Team	MITRE
2010-12-13	updated Name
2010-09-27	CWE Content Team	MITRE
2010-09-27	updated Potential_Mitigations, Relationships
2010-06-21	CWE Content Team	MITRE
2010-06-21	updated Potential_Mitigations
2010-02-16	CWE Content Team	MITRE
2010-02-16	updated Alternate_Terms, Applicable_Platforms, Demonstrative_Examples, Detection_Factors, Potential_Mitigations, References, Relationships, Taxonomy_Mappings
2009-12-28	CWE Content Team	MITRE
2009-12-28	updated Common_Consequences, Demonstrative_Examples, Detection_Factors, Observed_Examples
2009-10-29	CWE Content Team	MITRE
2009-10-29	updated Applicable_Platforms, Common_Consequences, Demonstrative_Examples, Description, Relationships, Time_of_Introduction
2009-07-27	CWE Content Team	MITRE
2009-07-27	updated Observed_Examples
2009-05-27	CWE Content Team	MITRE
2009-05-27	updated Demonstrative_Examples
2009-03-10	CWE Content Team	MITRE
2009-03-10	updated Potential_Mitigations
2009-01-12	CWE Content Team	MITRE
2009-01-12	updated Applicable_Platforms, Common_Consequences, Demonstrative_Examples, Likelihood_of_Exploit, Name, Potential_Mitigations, References, Relationships
2008-11-24	CWE Content Team	MITRE
2008-11-24	updated Relationships, Taxonomy_Mappings
2008-10-14	CWE Content Team	MITRE
2008-10-14	updated Relationships
2008-09-08	CWE Content Team	MITRE
2008-09-08	updated Description, Relationships, Taxonomy_Mappings
2008-08-15		Veracode
2008-08-15	Suggested OWASP Top Ten 2004 mapping
2008-07-01	Eric Dalci	Cigital
2008-07-01	updated Time_of_Introduction
Previous Entry Names
Change Date	Previous Entry Name
2008-04-11	Buffer Errors
2009-01-12	Failure to Constrain Operations within the Bounds of an Allocated Memory Buffer
2010-12-13	Failure to Constrain Operations within the Bounds of a Memory Buffer

Weakness ID: 662

View customized information:

Description

Extended Description

Synchronization refers to a variety of behaviors and mechanisms that allow two or more independently-operating processes or threads to ensure that they operate on shared resources in predictable ways that do not interfere with each other. Some shared resource operations cannot be executed atomically; that is, multiple steps must be guaranteed to execute sequentially, without any interference by other processes. Synchronization mechanisms vary widely, but they may include locking, mutexes, and semaphores. When a multi-step operation on a shared resource cannot be guaranteed to execute independent of interference, then the resulting behavior can be unpredictable. Improper synchronization could lead to data or memory corruption, denial of service, etc.

Common Consequences

Impact	Details
Modify Application Data; Read Application Data; Alter Execution Logic	Scope: Integrity, Confidentiality, Other

Potential Mitigations

Phase(s)	Mitigation
Implementation	Use industry standard APIs to synchronize your code.

Relationships

Relevant to the view "Research Concepts" (View-1000)

Nature	Type	ID	Name
ChildOf	Pillar - a weakness that is the most abstract type of weakness and represents a theme for all class/base/variant weaknesses related to it. A Pillar is different from a Category as a Pillar is still technically a type of weakness that describes a mistake, while a Category represents a common characteristic used to group related things.	664	Improper Control of a Resource Through its Lifetime
ChildOf	Pillar - a weakness that is the most abstract type of weakness and represents a theme for all class/base/variant weaknesses related to it. A Pillar is different from a Category as a Pillar is still technically a type of weakness that describes a mistake, while a Category represents a common characteristic used to group related things.	691	Insufficient Control Flow Management
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	663	Use of a Non-reentrant Function in a Concurrent Context
ParentOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	667	Improper Locking
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	820	Missing Synchronization
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	821	Incorrect Synchronization
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	1058	Invokable Control Element in Multi-Thread Context with non-Final Static Storable or Member Element
CanPrecede	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	362	Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

Relevant to the view "Weaknesses for Simplified Mapping of Published Vulnerabilities" (View-1003)

Nature	Type	ID	Name
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1003	Weaknesses for Simplified Mapping of Published Vulnerabilities
ParentOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	667	Improper Locking

Relevant to the view "CISQ Quality Measures (2020)" (View-1305)

Nature	Type	ID	Name
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	366	Race Condition within a Thread
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	543	Use of Singleton Pattern Without Synchronization in a Multithreaded Context
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	567	Unsynchronized Access to Shared Data in a Multithreaded Context
ParentOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	667	Improper Locking
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	764	Multiple Locks of a Critical Resource
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	820	Missing Synchronization
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	821	Incorrect Synchronization
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	833	Deadlock
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	1058	Invokable Control Element in Multi-Thread Context with non-Final Static Storable or Member Element
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	1096	Singleton Class Instance Creation without Proper Locking or Synchronization

Relevant to the view "CISQ Data Protection Measures" (View-1340)

Nature	Type	ID	Name
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	366	Race Condition within a Thread
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	543	Use of Singleton Pattern Without Synchronization in a Multithreaded Context
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	567	Unsynchronized Access to Shared Data in a Multithreaded Context
ParentOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	667	Improper Locking
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	764	Multiple Locks of a Critical Resource
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	820	Missing Synchronization
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	821	Incorrect Synchronization
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	1058	Invokable Control Element in Multi-Thread Context with non-Final Static Storable or Member Element
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	1096	Singleton Class Instance Creation without Proper Locking or Synchronization

Modes Of Introduction

Phase	Note
Architecture and Design
Implementation

Demonstrative Examples

Example 1

The following function attempts to acquire a lock in order to perform operations on a shared resource.

(bad code)

Example Language: C

void f(pthread_mutex_t *mutex) {

pthread_mutex_lock(mutex);

/* access shared resource */

pthread_mutex_unlock(mutex);

}

(good code)

Example Language: C

int f(pthread_mutex_t *mutex) {

int result;

result = pthread_mutex_lock(mutex);
if (0 != result)

return result;

/* access shared resource */

return pthread_mutex_unlock(mutex);

}

Example 2

The following code intends to fork a process, then have both the parent and child processes print a single line.

(bad code)

Example Language: C

static void print (char * string) {

char * word;
int counter;
for (word = string; counter = *word++; ) {

putc(counter, stdout);
fflush(stdout);
/* Make timing window a little larger... */

sleep(1);

}

}

int main(void) {

pid_t pid;

pid = fork();
if (pid == -1) {

exit(-2);

}
else if (pid == 0) {

print("child\n");

}
else {

print("PARENT\n");

}
exit(0);

}

One might expect the code to print out something like:

PARENT

child

However, because the parent and child are executing concurrently, and stdout is flushed each time a character is printed, the output might be mixed together, such as:

PcAhRiElNdT

[blank line]

Selected Observed Examples

Reference	Description
CVE-2021-1782	Chain: improper locking (CWE-667) leads to race condition (CWE-362), as exploited in the wild per CISA KEV.
CVE-2009-0935	Attacker provides invalid address to a memory-reading function, causing a mutex to be unlocked twice

Memberships

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	745	CERT C Secure Coding Standard (2008) Chapter 12 - Signals (SIG)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	852	The CERT Oracle Secure Coding Standard for Java (2011) Chapter 9 - Visibility and Atomicity (VNA)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	879	CERT C++ Secure Coding Section 11 - Signals (SIG)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	986	SFP Secondary Cluster: Missing Lock
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1142	SEI CERT Oracle Secure Coding Standard for Java - Guidelines 08. Visibility and Atomicity (VNA)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1166	SEI CERT C Coding Standard - Guidelines 11. Signals (SIG)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1306	CISQ Quality Measures - Reliability
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1308	CISQ Quality Measures - Security
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1340	CISQ Data Protection Measures
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1416	Comprehensive Categorization: Resource Lifecycle Management

Vulnerability Mapping Notes

Usage	DISCOURAGED (this CWE ID should not be used to map to real-world vulnerabilities)
Reason	Abstraction
Rationale	This CWE entry is a level-1 Class (i.e., a child of a Pillar). It might have lower-level children that would be more appropriate
Comments	Examine children of this entry to see if there is a better fit

Notes

Maintenance

Deeper research is necessary for synchronization and related mechanisms, including locks, mutexes, semaphores, and other mechanisms. Multiple entries are dependent on this research, which includes relationships to concurrency, race conditions, reentrant functions, etc. CWE-662 and its children - including CWE-667, CWE-820, CWE-821, and others - may need to be modified significantly, along with their relationships.

Taxonomy Mappings

Mapped Taxonomy Name	Node ID	Fit	Mapped Node Name
CERT C Secure Coding	SIG00-C		Mask signals handled by noninterruptible signal handlers
CERT C Secure Coding	SIG31-C	CWE More Abstract	Do not access shared objects in signal handlers
CLASP			State synchronization error
The CERT Oracle Secure Coding Standard for Java (2011)	VNA03-J		Do not assume that a group of calls to independently atomic methods is atomic
Software Fault Patterns	SFP19		Missing Lock

Related Attack Patterns

CAPEC-ID	Attack Pattern Name
CAPEC-25	Forced Deadlock
CAPEC-26	Leveraging Race Conditions
CAPEC-27	Leveraging Race Conditions via Symbolic Links
CAPEC-29	Leveraging Time-of-Check and Time-of-Use (TOCTOU) Race Conditions

Content History

Submissions
Submission Date	Submitter	Organization
2008-04-11 (CWE Draft 9, 2008-04-11)	CWE Community
2008-04-11 (CWE Draft 9, 2008-04-11)	Submitted by members of the CWE community to extend early CWE versions
Modifications
Modification Date	Modifier	Organization
2024-02-29 (CWE 4.14, 2024-02-29)	CWE Content Team	MITRE
2024-02-29 (CWE 4.14, 2024-02-29)	updated Mapping_Notes
2023-10-26	CWE Content Team	MITRE
2023-10-26	updated Demonstrative_Examples, Observed_Examples
2023-06-29	CWE Content Team	MITRE
2023-06-29	updated Mapping_Notes
2023-04-27	CWE Content Team	MITRE
2023-04-27	updated Relationships
2023-01-31	CWE Content Team	MITRE
2023-01-31	updated Description
2020-12-10	CWE Content Team	MITRE
2020-12-10	updated Relationships
2020-08-20	CWE Content Team	MITRE
2020-08-20	updated Relationships
2020-02-24	CWE Content Team	MITRE
2020-02-24	updated Description, Relationships
2019-09-23	CWE Content Team	MITRE
2019-09-23	updated Description, Maintenance_Notes, Relationships
2019-06-20	CWE Content Team	MITRE
2019-06-20	updated Type
2019-01-03	CWE Content Team	MITRE
2019-01-03	updated Relationships, Taxonomy_Mappings
2017-11-08	CWE Content Team	MITRE
2017-11-08	updated Taxonomy_Mappings
2014-07-30	CWE Content Team	MITRE
2014-07-30	updated Relationships, Taxonomy_Mappings
2013-07-17	CWE Content Team	MITRE
2013-07-17	updated Relationships
2012-10-30	CWE Content Team	MITRE
2012-10-30	updated Potential_Mitigations
2012-05-11	CWE Content Team	MITRE
2012-05-11	updated Relationships
2011-09-13	CWE Content Team	MITRE
2011-09-13	updated Relationships, Taxonomy_Mappings
2011-06-01	CWE Content Team	MITRE
2011-06-01	updated Common_Consequences, Relationships, Taxonomy_Mappings
2010-12-13	CWE Content Team	MITRE
2010-12-13	updated Description, Relationships, Taxonomy_Mappings
2010-09-27	CWE Content Team	MITRE
2010-09-27	updated Name, Relationships
2009-05-27	CWE Content Team	MITRE
2009-05-27	updated Relationships
2009-03-10	CWE Content Team	MITRE
2009-03-10	updated Related_Attack_Patterns
2008-11-24	CWE Content Team	MITRE
2008-11-24	updated Relationships, Taxonomy_Mappings
2008-10-14	CWE Content Team	MITRE
2008-10-14	updated Relationships
2008-09-08	CWE Content Team	MITRE
2008-09-08	updated Relationships
2008-07-01	Eric Dalci	Cigital
2008-07-01	updated Potential_Mitigations, Time_of_Introduction
Previous Entry Names
Change Date	Previous Entry Name
2010-09-27	Insufficient Synchronization

Weakness ID: 129

Vulnerability Mapping: ALLOWED This CWE ID may be used to map to real-world vulnerabilities
Abstraction: Variant Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.

View customized information:

Description

Alternate Terms

out-of-bounds array index
index-out-of-range
array index underflow

Common Consequences

Impact	Details
DoS: Crash, Exit, or Restart	Scope: Integrity, Availability Use of an index that is outside the bounds of an array will very likely result in the corruption of relevant memory and perhaps instructions, leading to a crash, if the values are outside of the valid memory area.
Modify Memory	Scope: Integrity If the memory corrupted is data, rather than instructions, the system will continue to function with improper values.
Modify Memory; Read Memory	Scope: Confidentiality, Integrity Use of an index that is outside the bounds of an array can also trigger out-of-bounds read or write operations, or operations on the wrong objects; i.e., "buffer overflows" are not always the result. This may result in the exposure or modification of sensitive data.
Execute Unauthorized Code or Commands	Scope: Integrity, Confidentiality, Availability If the memory accessible by the attacker can be effectively controlled, it may be possible to execute arbitrary code, as with a standard buffer overflow and possibly without the use of large inputs if a precise index can be controlled.
DoS: Crash, Exit, or Restart; Execute Unauthorized Code or Commands; Read Memory; Modify Memory	Scope: Integrity, Availability, Confidentiality A single fault could allow either an overflow (CWE-788) or underflow (CWE-786) of the array index. What happens next will depend on the type of operation being performed out of bounds, but can expose sensitive information, cause a system crash, or possibly lead to arbitrary code execution.

Potential Mitigations

Phase(s)	Mitigation
Architecture and Design	Strategy: Input Validation Use an input validation framework such as Struts or the OWASP ESAPI Validation API. Note that using a framework does not automatically address all input validation problems; be mindful of weaknesses that could arise from misusing the framework itself (CWE-1173).
Architecture and Design	For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server. Even though client-side checks provide minimal benefits with respect to server-side security, they are still useful. First, they can support intrusion detection. If the server receives input that should have been rejected by the client, then it may be an indication of an attack. Second, client-side error-checking can provide helpful feedback to the user about the expectations for valid input. Third, there may be a reduction in server-side processing time for accidental input errors, although this is typically a small savings.
Requirements	Strategy: Language Selection Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, Ada allows the programmer to constrain the values of a variable and languages such as Java and Ruby will allow the programmer to handle exceptions when an out-of-bounds index is accessed.
Operation; Build and Compilation	Strategy: Environment Hardening Run or compile the software using features or extensions that randomly arrange the positions of a program's executable and libraries in memory. Because this makes the addresses unpredictable, it can prevent an attacker from reliably jumping to exploitable code. Examples include Address Space Layout Randomization (ASLR) [REF-58] [REF-60] and Position-Independent Executables (PIE) [REF-64]. Imported modules may be similarly realigned if their default memory addresses conflict with other modules, in a process known as "rebasing" (for Windows) and "prelinking" (for Linux) [REF-1332] using randomly generated addresses. ASLR for libraries cannot be used in conjunction with prelink since it would require relocating the libraries at run-time, defeating the whole purpose of prelinking. For more information on these techniques see D3-SAOR (Segment Address Offset Randomization) from D3FEND [REF-1335]. Effectiveness: Defense in Depth Note: These techniques do not provide a complete solution. For instance, exploits frequently use a bug that discloses memory addresses in order to maximize reliability of code execution [REF-1337]. It has also been shown that a side-channel attack can bypass ASLR [REF-1333]
Operation	Strategy: Environment Hardening Use a CPU and operating system that offers Data Execution Protection (using hardware NX or XD bits) or the equivalent techniques that simulate this feature in software, such as PaX [REF-60] [REF-61]. These techniques ensure that any instruction executed is exclusively at a memory address that is part of the code segment. For more information on these techniques see D3-PSEP (Process Segment Execution Prevention) from D3FEND [REF-1336]. Effectiveness: Defense in Depth Note: This is not a complete solution, since buffer overflows could be used to overwrite nearby variables to modify the software's state in dangerous ways. In addition, it cannot be used in cases in which self-modifying code is required. Finally, an attack could still cause a denial of service, since the typical response is to exit the application.
Implementation	Strategy: Input Validation Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does. When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue." Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright. When accessing a user-controlled array index, use a stringent range of values that are within the target array. Make sure that you do not allow negative values to be used. That is, verify the minimum as well as the maximum of the range of acceptable values.
Implementation	Be especially careful to validate all input when invoking code that crosses language boundaries, such as from an interpreted language to native code. This could create an unexpected interaction between the language boundaries. Ensure that you are not violating any of the expectations of the language with which you are interfacing. For example, even though Java may not be susceptible to buffer overflows, providing a large argument in a call to native code might trigger an overflow.
Architecture and Design; Operation	Strategy: Environment Hardening Run your code using the lowest privileges that are required to accomplish the necessary tasks [REF-76]. If possible, create isolated accounts with limited privileges that are only used for a single task. That way, a successful attack will not immediately give the attacker access to the rest of the software or its environment. For example, database applications rarely need to run as the database administrator, especially in day-to-day operations.
Architecture and Design; Operation	Strategy: Sandbox or Jail Run the code in a "jail" or similar sandbox environment that enforces strict boundaries between the process and the operating system. This may effectively restrict which files can be accessed in a particular directory or which commands can be executed by the software. OS-level examples include the Unix chroot jail, AppArmor, and SELinux. In general, managed code may provide some protection. For example, java.io.FilePermission in the Java SecurityManager allows the software to specify restrictions on file operations. This may not be a feasible solution, and it only limits the impact to the operating system; the rest of the application may still be subject to compromise. Be careful to avoid CWE-243 and other weaknesses related to jails. Effectiveness: Limited Note: The effectiveness of this mitigation depends on the prevention capabilities of the specific sandbox or jail being used and might only help to reduce the scope of an attack, such as restricting the attacker to certain system calls or limiting the portion of the file system that can be accessed.

Relationships

Relevant to the view "Research Concepts" (View-1000)

Nature	Type	ID	Name
ChildOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	1285	Improper Validation of Specified Index, Position, or Offset in Input
CanPrecede	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	119	Improper Restriction of Operations within the Bounds of a Memory Buffer
CanPrecede	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	789	Memory Allocation with Excessive Size Value
CanPrecede	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	823	Use of Out-of-range Pointer Offset

Relevant to the view "Weaknesses for Simplified Mapping of Published Vulnerabilities" (View-1003)

Nature	Type	ID	Name
ChildOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	20	Improper Input Validation

Modes Of Introduction

Phase	Note
Implementation

Applicable Platforms

Languages

C (Often Prevalent)

C++ (Often Prevalent)

Class: Not Language-Specific (Undetermined Prevalence)

Likelihood Of Exploit

High

Demonstrative Examples

Example 1

In the code snippet below, an untrusted integer value is used to reference an object in an array.

(bad code)

Example Language: Java

public String getValue(int index) {

return array[index];

}

If index is outside of the range of the array, this may result in an ArrayIndexOutOfBounds Exception being raised.

Example 2

The following example takes a user-supplied value to allocate an array of objects and then operates on the array.

(bad code)

Example Language: Java

private void buildList ( int untrustedListSize ){

if ( 0 > untrustedListSize ){

die("Negative value supplied for list size, die evil hacker!");

}
Widget[] list = new Widget [ untrustedListSize ];
list[0] = new Widget();

}

Example 3

In the following code, the method retrieves a value from an array at a specific array index location that is given as an input parameter to the method

(bad code)

Example Language: C

int getValueFromArray(int *array, int len, int index) {

int value;

// check that the array index is less than the maximum

// length of the array
if (index < len) {

// get the value at the specified index of the array
value = array[index];

}
// if array index is invalid then output error message

// and return value indicating error
else {

printf("Value is: %d\n", array[index]);
value = -1;

}

return value;

}

(good code)

Example Language: C

...

// check that the array index is within the correct

// range of values for the array
if (index >= 0 && index < len) {

...

Example 4

The following example retrieves the sizes of messages for a pop3 mail server. The message sizes are retrieved from a socket that returns in a buffer the message number and the message size, the message number (num) and size (size) are extracted from the buffer and the message size is placed into an array using the message number for the array index.

(bad code)

Example Language: C

/* capture the sizes of all messages */
int getsizes(int sock, int count, int *sizes) {

...
char buf[BUFFER_SIZE];
int ok;
int num, size;

// read values from socket and added to sizes array
while ((ok = gen_recv(sock, buf, sizeof(buf))) == 0)
{

// continue read from socket until buf only contains '.'
if (DOTLINE(buf))

break;

else if (sscanf(buf, "%d %d", &num, &size) == 2)

sizes[num - 1] = size;

}

...

}

In this example the message number retrieved from the buffer could be a value that is outside the allowable range of indices for the array and could possibly be a negative number. Without proper validation of the value to be used for the array index an array overflow could occur and could potentially lead to unauthorized access to memory addresses and system crashes. The value of the array index should be validated to ensure that it is within the allowable range of indices for the array as in the following code.

(good code)

Example Language: C

/* capture the sizes of all messages */
int getsizes(int sock, int count, int *sizes) {

...
char buf[BUFFER_SIZE];
int ok;
int num, size;

// read values from socket and added to sizes array
while ((ok = gen_recv(sock, buf, sizeof(buf))) == 0)
{

// continue read from socket until buf only contains '.'
if (DOTLINE(buf))

break;

else if (sscanf(buf, "%d %d", &num, &size) == 2) {

if (num > 0 && num <= (unsigned)count)

sizes[num - 1] = size;

else

/* warn about possible attempt to induce buffer overflow */
report(stderr, "Warning: ignoring bogus data for message sizes returned by server.\n");

}

...

}

Example 5

In the following example the method displayProductSummary is called from a Web service servlet to retrieve product summary information for display to the user. The servlet obtains the integer value of the product number from the user and passes it to the displayProductSummary method. The displayProductSummary method passes the integer value of the product number to the getProductSummary method which obtains the product summary from the array object containing the project summaries using the integer value of the product number as the array index.

(bad code)

Example Language: Java

// Method called from servlet to obtain product information
public String displayProductSummary(int index) {

String productSummary = new String("");

try {

String productSummary = getProductSummary(index);

} catch (Exception ex) {...}

return productSummary;

}

public String getProductSummary(int index) {

return products[index];

}

In this example the integer value used as the array index that is provided by the user may be outside the allowable range of indices for the array which may provide unexpected results or cause the application to fail. The integer value used for the array index should be validated to ensure that it is within the allowable range of indices for the array as in the following code.

(good code)

Example Language: Java

// Method called from servlet to obtain product information
public String displayProductSummary(int index) {

String productSummary = new String("");

try {

String productSummary = getProductSummary(index);

} catch (Exception ex) {...}

return productSummary;

}

public String getProductSummary(int index) {

String productSummary = "";

if ((index >= 0) && (index < MAX_PRODUCTS)) {

productSummary = products[index];

}
else {

System.err.println("index is out of bounds");
throw new IndexOutOfBoundsException();

}

return productSummary;

}

An alternative in Java would be to use one of the collection objects such as ArrayList that will automatically generate an exception if an attempt is made to access an array index that is out of bounds.

(good code)

Example Language: Java

ArrayList productArray = new ArrayList(MAX_PRODUCTS);
...
try {

productSummary = (String) productArray.get(index);

} catch (IndexOutOfBoundsException ex) {...}

Example 6

The following example asks a user for an offset into an array to select an item.

(bad code)

Example Language: C

int main (int argc, char **argv) {

char *items[] = {"boat", "car", "truck", "train"};
int index = GetUntrustedOffset();
printf("You selected %s\n", items[index-1]);

}

The programmer allows the user to specify which element in the list to select, however an attacker can provide an out-of-bounds offset, resulting in a buffer over-read (CWE-126).

Selected Observed Examples

Reference	Description
CVE-2005-0369	large ID in packet used as array index
CVE-2001-1009	negative array index as argument to POP LIST command
CVE-2003-0721	Integer signedness error leads to negative array index
CVE-2004-1189	product does not properly track a count and a maximum number, which can lead to resultant array index overflow.
CVE-2007-5756	Chain: device driver for packet-capturing software allows access to an unintended IOCTL with resultant array index error.
CVE-2005-2456	Chain: array index error (CWE-129) leads to deadlock (CWE-833)

Weakness Ordinalities

Ordinality

Description

Resultant

(where the weakness is typically related to the presence of some other weaknesses)

The most common condition situation leading to an out-of-bounds array index is the use of loop index variables as buffer indexes. If the end condition for the loop is subject to a flaw, the index can grow or shrink unbounded, therefore causing a buffer overflow or underflow. Another common situation leading to this condition is the use of a function's return value, or the resulting value of a calculation directly as an index in to a buffer.

Detection Methods

Method	Details
Automated Static Analysis	This weakness can often be detected using automated static analysis tools. Many modern tools use data flow analysis or constraint-based techniques to minimize the number of false positives. Automated static analysis generally does not account for environmental considerations when reporting out-of-bounds memory operations. This can make it difficult for users to determine which warnings should be investigated first. For example, an analysis tool might report array index errors that originate from command line arguments in a program that is not expected to run with setuid or other special privileges. Effectiveness: High Note:This is not a perfect solution, since 100% accuracy and coverage are not feasible.
Automated Dynamic Analysis	This weakness can be detected using dynamic tools and techniques that interact with the software using large test suites with many diverse inputs, such as fuzz testing (fuzzing), robustness testing, and fault injection. The software's operation may slow down, but it should not become unstable, crash, or generate incorrect results.
Black Box	Black box methods might not get the needed code coverage within limited time constraints, and a dynamic test might not produce any noticeable side effects even if it is successful.

Affected Resources

Memory

Memberships

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	738	CERT C Secure Coding Standard (2008) Chapter 5 - Integers (INT)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	740	CERT C Secure Coding Standard (2008) Chapter 7 - Arrays (ARR)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	802	2010 Top 25 - Risky Resource Management
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	867	2011 Top 25 - Weaknesses On the Cusp
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	872	CERT C++ Secure Coding Section 04 - Integers (INT)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	874	CERT C++ Secure Coding Section 06 - Arrays and the STL (ARR)
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	884	CWE Cross-section
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	970	SFP Secondary Cluster: Faulty Buffer Access
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1131	CISQ Quality Measures (2016) - Security
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1160	SEI CERT C Coding Standard - Guidelines 06. Arrays (ARR)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1179	SEI CERT Perl Coding Standard - Guidelines 01. Input Validation and Data Sanitization (IDS)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1308	CISQ Quality Measures - Security
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1340	CISQ Data Protection Measures
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1399	Comprehensive Categorization: Memory Safety

Vulnerability Mapping Notes

Usage	ALLOWED (this CWE ID may be used to map to real-world vulnerabilities)
Reason	Acceptable-Use
Rationale	This CWE entry is at the Variant level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.
Comments	Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction.

Notes

Relationship

This weakness can precede uncontrolled memory allocation (CWE-789) in languages that automatically expand an array when an index is used that is larger than the size of the array, such as JavaScript.

Theoretical

An improperly validated array index might lead directly to the always-incorrect behavior of "access of array using out-of-bounds index."

Taxonomy Mappings

Mapped Taxonomy Name	Node ID	Fit	Mapped Node Name
CLASP			Unchecked array indexing
PLOVER			INDEX - Array index overflow
CERT C Secure Coding	ARR00-C		Understand how arrays work
CERT C Secure Coding	ARR30-C	CWE More Specific	Do not form or use out-of-bounds pointers or array subscripts
CERT C Secure Coding	ARR38-C		Do not add or subtract an integer to a pointer if the resulting value does not refer to a valid array element
CERT C Secure Coding	INT32-C		Ensure that operations on signed integers do not result in overflow
SEI CERT Perl Coding Standard	IDS32-PL	Imprecise	Validate any integer that is used as an array index
OMG ASCSM	ASCSM-CWE-129
Software Fault Patterns	SFP8		Faulty Buffer Access

Related Attack Patterns

CAPEC-ID	Attack Pattern Name
CAPEC-100	Overflow Buffers

References

[REF-7]	Michael Howard and David LeBlanc. "Writing Secure Code". Chapter 5, "Array Indexing Errors" Page 144. 2nd Edition. Microsoft Press. 2002-12-04. <https://www.microsoftpressstore.com/store/writing-secure-code-9780735617223>.
[REF-96]	Jason Lam. "Top 25 Series - Rank 14 - Improper Validation of Array Index". SANS Software Security Institute. 2010-03-12. <https://web.archive.org/web/20100316064026/http://blogs.sans.org/appsecstreetfighter/2010/03/12/top-25-series-rank-14-improper-validation-of-array-index/>. (URL validated: 2023-04-07)
[REF-58]	Michael Howard. "Address Space Layout Randomization in Windows Vista". <https://learn.microsoft.com/en-us/archive/blogs/michael_howard/address-space-layout-randomization-in-windows-vista>. (URL validated: 2023-04-07)
[REF-60]	"PaX". <https://en.wikipedia.org/wiki/Executable_space_protection#PaX>. (URL validated: 2023-04-07)
[REF-61]	Microsoft. "Understanding DEP as a mitigation technology part 1". <https://msrc.microsoft.com/blog/2009/06/understanding-dep-as-a-mitigation-technology-part-1/>. (URL validated: 2023-04-07)
[REF-76]	Sean Barnum and Michael Gegick. "Least Privilege". 2005-09-14. <https://web.archive.org/web/20211209014121/https://www.cisa.gov/uscert/bsi/articles/knowledge/principles/least-privilege>. (URL validated: 2023-04-07)
[REF-44]	Michael Howard, David LeBlanc and John Viega. "24 Deadly Sins of Software Security". "Sin 5: Buffer Overruns." Page 89. McGraw-Hill. 2010.
[REF-64]	Grant Murphy. "Position Independent Executables (PIE)". Red Hat. 2012-11-28. <https://www.redhat.com/en/blog/position-independent-executables-pie>. (URL validated: 2023-04-07)
[REF-962]	Object Management Group (OMG). "Automated Source Code Security Measure (ASCSM)". ASCSM-CWE-129. 2016-01. <http://www.omg.org/spec/ASCSM/1.0/>.
[REF-18]	Secure Software, Inc.. "The CLASP Application Security Process". 2005. <https://cwe.mitre.org/documents/sources/TheCLASPApplicationSecurityProcess.pdf>. (URL validated: 2024-11-17)
[REF-1332]	John Richard Moser. "Prelink and address space randomization". 2006-07-05. <https://lwn.net/Articles/190139/>. (URL validated: 2023-04-26)
[REF-1333]	Dmitry Evtyushkin, Dmitry Ponomarev, Nael Abu-Ghazaleh. "Jump Over ASLR: Attacking Branch Predictors to Bypass ASLR". 2016. <http://www.cs.ucr.edu/~nael/pubs/micro16.pdf>. (URL validated: 2023-04-26)
[REF-1335]	D3FEND. "Segment Address Offset Randomization (D3-SAOR)". 2023. <https://d3fend.mitre.org/technique/d3f:SegmentAddressOffsetRandomization/>. (URL validated: 2023-04-26)
[REF-1336]	D3FEND. "Process Segment Execution Prevention (D3-PSEP)". 2023. <https://d3fend.mitre.org/technique/d3f:ProcessSegmentExecutionPrevention/>. (URL validated: 2023-04-26)
[REF-1337]	Alexander Sotirov and Mark Dowd. "Bypassing Browser Memory Protections: Setting back browser security by 10 years". Memory information leaks. 2008. <https://www.blackhat.com/presentations/bh-usa-08/Sotirov_Dowd/bh08-sotirov-dowd.pdf>. (URL validated: 2023-04-26)

Content History

Submissions
Submission Date	Submitter	Organization
2006-07-19 (CWE Draft 3, 2006-07-19)	CLASP
2006-07-19 (CWE Draft 3, 2006-07-19)
Modifications
Modification Date	Modifier	Organization
2023-06-29	CWE Content Team	MITRE
2023-06-29	updated Mapping_Notes
2023-04-27	CWE Content Team	MITRE
2023-04-27	updated Potential_Mitigations, References, Relationships
2022-10-13	CWE Content Team	MITRE
2022-10-13	updated References, Relationships, Taxonomy_Mappings
2021-03-15	CWE Content Team	MITRE
2021-03-15	updated References, Relationships
2020-12-10	CWE Content Team	MITRE
2020-12-10	updated Relationships
2020-08-20	CWE Content Team	MITRE
2020-08-20	updated Potential_Mitigations, Relationships
2020-06-25	CWE Content Team	MITRE
2020-06-25	updated Demonstrative_Examples, Potential_Mitigations, Relationships, Type
2020-02-24	CWE Content Team	MITRE
2020-02-24	updated Potential_Mitigations, Relationships, Taxonomy_Mappings
2019-09-19	CWE Content Team	MITRE
2019-09-19	updated Potential_Mitigations
2019-01-03	CWE Content Team	MITRE
2019-01-03	updated References, Relationships, Taxonomy_Mappings
2018-03-27	CWE Content Team	MITRE
2018-03-27	updated References
2017-11-08	CWE Content Team	MITRE
2017-11-08	updated Causal_Nature, References, Relationships, Taxonomy_Mappings
2015-12-07	CWE Content Team	MITRE
2015-12-07	updated Relationships
2014-07-30	CWE Content Team	MITRE
2014-07-30	updated Relationships, Taxonomy_Mappings
2014-02-18	CWE Content Team	MITRE
2014-02-18	updated Potential_Mitigations, References
2012-10-30	CWE Content Team	MITRE
2012-10-30	updated Potential_Mitigations
2012-05-11	CWE Content Team	MITRE
2012-05-11	updated Demonstrative_Examples, Potential_Mitigations, References, Relationships
2011-09-13	CWE Content Team	MITRE
2011-09-13	updated Relationships, Taxonomy_Mappings
2011-06-27	CWE Content Team	MITRE
2011-06-27	updated Relationships
2011-06-01	CWE Content Team	MITRE
2011-06-01	updated Common_Consequences
2011-03-29	CWE Content Team	MITRE
2011-03-29	updated Common_Consequences, Demonstrative_Examples, Weakness_Ordinalities
2010-12-13	CWE Content Team	MITRE
2010-12-13	updated Demonstrative_Examples, Observed_Examples, Potential_Mitigations
2010-09-27	CWE Content Team	MITRE
2010-09-27	updated Potential_Mitigations, Relationship_Notes, Relationships
2010-06-21	CWE Content Team	MITRE
2010-06-21	updated Common_Consequences, Potential_Mitigations, References
2010-04-05	CWE Content Team	MITRE
2010-04-05	updated Related_Attack_Patterns
2010-02-16	CWE Content Team	MITRE
2010-02-16	updated Applicable_Platforms, Demonstrative_Examples, Detection_Factors, Likelihood_of_Exploit, Potential_Mitigations, References, Related_Attack_Patterns, Relationships
2009-12-28	CWE Content Team	MITRE
2009-12-28	updated Applicable_Platforms, Common_Consequences, Observed_Examples, Other_Notes, Potential_Mitigations, Theoretical_Notes, Weakness_Ordinalities
2009-10-29	CWE Content Team	MITRE
2009-10-29	updated Description, Name, Relationships
2009-01-12	CWE Content Team	MITRE
2009-01-12	updated Common_Consequences
2008-11-24	CWE Content Team	MITRE
2008-11-24	updated Relationships, Taxonomy_Mappings
2008-09-08	CWE Content Team	MITRE
2008-09-08	updated Alternate_Terms, Applicable_Platforms, Common_Consequences, Relationships, Other_Notes, Taxonomy_Mappings, Weakness_Ordinalities
2008-07-01	Sean Eidemiller	Cigital
2008-07-01	added/updated demonstrative examples
Previous Entry Names
Change Date	Previous Entry Name
2009-10-29	Unchecked Array Indexing

Weakness ID: 682

Vulnerability Mapping: DISCOURAGED This CWE ID should not be used to map to real-world vulnerabilities
Abstraction: Pillar Pillar - a weakness that is the most abstract type of weakness and represents a theme for all class/base/variant weaknesses related to it. A Pillar is different from a Category as a Pillar is still technically a type of weakness that describes a mistake, while a Category represents a common characteristic used to group related things.

View customized information:

Description

The product performs a calculation that generates incorrect or unintended results that are later used in security-critical decisions or resource management.

Extended Description

When product performs a security-critical calculation incorrectly, it might lead to incorrect resource allocations, incorrect privilege assignments, or failed comparisons among other things. Many of the direct results of an incorrect calculation can lead to even larger problems such as failed protection mechanisms or even arbitrary code execution.

Common Consequences

Impact	Details
DoS: Crash, Exit, or Restart	Scope: Availability If the incorrect calculation causes the program to move into an unexpected state, it may lead to a crash or impairment of service.
DoS: Crash, Exit, or Restart; DoS: Resource Consumption (Other); Execute Unauthorized Code or Commands	Scope: Integrity, Confidentiality, Availability If the incorrect calculation is used in the context of resource allocation, it could lead to an out-of-bounds operation (CWE-119) leading to a crash or even arbitrary code execution. Alternatively, it may result in an integer overflow (CWE-190) and / or a resource consumption problem (CWE-400).
Gain Privileges or Assume Identity	Scope: Access Control In the context of privilege or permissions assignment, an incorrect calculation can provide an attacker with access to sensitive resources.
Bypass Protection Mechanism	Scope: Access Control If the incorrect calculation leads to an insufficient comparison (CWE-697), it may compromise a protection mechanism such as a validation routine and allow an attacker to bypass the security-critical code.

Potential Mitigations

Phase(s)	Mitigation
Implementation	Understand your programming language's underlying representation and how it interacts with numeric calculation. Pay close attention to byte size discrepancies, precision, signed/unsigned distinctions, truncation, conversion and casting between types, "not-a-number" calculations, and how your language handles numbers that are too large or too small for its underlying representation.
Implementation	Strategy: Input Validation Perform input validation on any numeric input by ensuring that it is within the expected range. Enforce that the input meets both the minimum and maximum requirements for the expected range.
Implementation	Use the appropriate type for the desired action. For example, in C/C++, only use unsigned types for values that could never be negative, such as height, width, or other numbers related to quantity.
Architecture and Design	Strategy: Language Selection Use languages, libraries, or frameworks that make it easier to handle numbers without unexpected consequences. Examples include safe integer handling packages such as SafeInt (C++) or IntegerLib (C or C++).
Architecture and Design	Strategy: Libraries or Frameworks Use languages, libraries, or frameworks that make it easier to handle numbers without unexpected consequences. Examples include safe integer handling packages such as SafeInt (C++) or IntegerLib (C or C++).
Implementation	Strategy: Compilation or Build Hardening Examine compiler warnings closely and eliminate problems with potential security implications, such as signed / unsigned mismatch in memory operations, or use of uninitialized variables. Even if the weakness is rarely exploitable, a single failure may lead to the compromise of the entire system.
Testing	Use automated static analysis tools that target this type of weakness. Many modern techniques use data flow analysis to minimize the number of false positives. This is not a perfect solution, since 100% accuracy and coverage are not feasible.
Testing	Use dynamic tools and techniques that interact with the product using large test suites with many diverse inputs, such as fuzz testing (fuzzing), robustness testing, and fault injection. The product's operation may slow down, but it should not become unstable, crash, or generate incorrect results.

Relationships

Relevant to the view "Research Concepts" (View-1000)

Nature	Type	ID	Name
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1000	Research Concepts
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	128	Wrap-around Error
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	131	Incorrect Calculation of Buffer Size
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	135	Incorrect Calculation of Multi-Byte String Length
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	190	Integer Overflow or Wraparound
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	191	Integer Underflow (Wrap or Wraparound)
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	193	Off-by-one Error
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	369	Divide By Zero
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	468	Incorrect Pointer Scaling
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	469	Use of Pointer Subtraction to Determine Size
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	1335	Incorrect Bitwise Shift of Integer
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	1339	Insufficient Precision or Accuracy of a Real Number
CanFollow	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	681	Incorrect Conversion between Numeric Types
CanFollow	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	839	Numeric Range Comparison Without Minimum Check
CanPrecede	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	170	Improper Null Termination

Relevant to the view "Weaknesses for Simplified Mapping of Published Vulnerabilities" (View-1003)

Nature	Type	ID	Name
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1003	Weaknesses for Simplified Mapping of Published Vulnerabilities
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	131	Incorrect Calculation of Buffer Size
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	190	Integer Overflow or Wraparound
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	191	Integer Underflow (Wrap or Wraparound)
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	193	Off-by-one Error
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	369	Divide By Zero

Relevant to the view "CISQ Quality Measures (2020)" (View-1305)

Nature	Type	ID	Name
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	131	Incorrect Calculation of Buffer Size
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	369	Divide By Zero

Relevant to the view "CISQ Data Protection Measures" (View-1340)

Nature	Type	ID	Name
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	131	Incorrect Calculation of Buffer Size
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	369	Divide By Zero

Modes Of Introduction

Phase	Note
Implementation

Applicable Platforms

Languages	Class: Not Language-Specific (Undetermined Prevalence)
Technologies	Class: Not Technology-Specific (Undetermined Prevalence)

Likelihood Of Exploit

High

Demonstrative Examples

Example 1

The following image processing code allocates a table for images.

(bad code)

Example Language: C

img_t table_ptr; /*struct containing img data, 10kB each*/
int num_imgs;
...
num_imgs = get_num_imgs();
table_ptr = (img_t*)malloc(sizeof(img_t)*num_imgs);
...

This code intends to allocate a table of size num_imgs, however as num_imgs grows large, the calculation determining the size of the list will eventually overflow (CWE-190). This will result in a very small list to be allocated instead. If the subsequent code operates on the list as if it were num_imgs long, it may result in many types of out-of-bounds problems (CWE-119).

Example 2

This code attempts to calculate a football team's average number of yards gained per touchdown.

(bad code)

Example Language: Java

...
int touchdowns = team.getTouchdowns();
int yardsGained = team.getTotalYardage();
System.out.println(team.getName() + " averages " + yardsGained / touchdowns + "yards gained for every touchdown scored");
...

The code does not consider the event that the team they are querying has not scored a touchdown, but has gained yardage. In that case, we should expect an ArithmeticException to be thrown by the JVM. This could lead to a loss of availability if our error handling code is not set up correctly.

Example 3

This example attempts to calculate the position of the second byte of a pointer.

(bad code)

Example Language: C

int *p = x;
char * second_char = (char *)(p + 1);

In this example, second_char is intended to point to the second byte of p. But, adding 1 to p actually adds sizeof(int) to p, giving a result that is incorrect (3 bytes off on 32-bit platforms). If the resulting memory address is read, this could potentially be an information leak. If it is a write, it could be a security-critical write to unauthorized memory-- whether or not it is a buffer overflow. Note that the above code may also be wrong in other ways, particularly in a little endian environment.

Selected Observed Examples

Reference	Description
CVE-2020-0022	chain: mobile phone Bluetooth implementation does not include offset when calculating packet length (CWE-682), leading to out-of-bounds write (CWE-787)
CVE-2004-1363	substitution overflow: buffer overflow using environment variables that are expanded after the length check is performed

Detection Methods

Method

Details

Manual Analysis

This weakness can be detected using tools and techniques that require manual (human) analysis, such as penetration testing, threat modeling, and interactive tools that allow the tester to record and modify an active session.

Specifically, manual static analysis is useful for evaluating the correctness of allocation calculations. This can be useful for detecting overflow conditions (CWE-190) or similar weaknesses that might have serious security impacts on the program.

Effectiveness: High

Note:These may be more effective than strictly automated techniques. This is especially the case with weaknesses that are related to design and business rules.

Memberships

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	738	CERT C Secure Coding Standard (2008) Chapter 5 - Integers (INT)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	739	CERT C Secure Coding Standard (2008) Chapter 6 - Floating Point (FLP)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	752	2009 Top 25 - Risky Resource Management
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	872	CERT C++ Secure Coding Section 04 - Integers (INT)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	873	CERT C++ Secure Coding Section 05 - Floating Point Arithmetic (FLP)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	977	SFP Secondary Cluster: Design
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1137	SEI CERT Oracle Secure Coding Standard for Java - Guidelines 03. Numeric Types and Operations (NUM)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1158	SEI CERT C Coding Standard - Guidelines 04. Integers (INT)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1159	SEI CERT C Coding Standard - Guidelines 05. Floating Point (FLP)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1306	CISQ Quality Measures - Reliability
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1308	CISQ Quality Measures - Security
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1340	CISQ Data Protection Measures
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1408	Comprehensive Categorization: Incorrect Calculation

Vulnerability Mapping Notes

Usage	DISCOURAGED (this CWE ID should not be used to map to real-world vulnerabilities)
Reason	Abstraction
Rationale	This CWE entry is extremely high-level, a Pillar. In many cases, lower-level children or descendants are more appropriate. However, sometimes this weakness is forced to be used due to the lack of in-depth weakness research. See Research Gaps.
Comments	Where feasible, consider children or descendants of this entry instead.

Notes

Research Gap

Weaknesses related to this Pillar appear to be under-studied, especially with respect to classification schemes. Input from academic and other communities could help identify and resolve gaps or organizational difficulties within CWE.

Taxonomy Mappings

Mapped Taxonomy Name	Node ID	Fit	Mapped Node Name
CERT C Secure Coding	FLP32-C	CWE More Abstract	Prevent or detect domain and range errors in math functions
CERT C Secure Coding	INT07-C		Use only explicitly signed or unsigned char type for numeric values
CERT C Secure Coding	INT13-C		Use bitwise operators only on unsigned operands
CERT C Secure Coding	INT33-C	CWE More Abstract	Ensure that division and remainder operations do not result in divide-by-zero errors
CERT C Secure Coding	INT34-C	CWE More Abstract	Do not shift an expression by a negative number of bits or by greater than or equal to the number of bits that exist in the operand

Related Attack Patterns

CAPEC-ID	Attack Pattern Name
CAPEC-128	Integer Attacks
CAPEC-129	Pointer Manipulation

References

[REF-106]	David LeBlanc and Niels Dekker. "SafeInt". <http://safeint.codeplex.com/>.
[REF-44]	Michael Howard, David LeBlanc and John Viega. "24 Deadly Sins of Software Security". "Sin 7: Integer Overflows." Page 119. McGraw-Hill. 2010.
[REF-62]	Mark Dowd, John McDonald and Justin Schuh. "The Art of Software Security Assessment". Chapter 6, "Signed Integer Boundaries", Page 220. 1st Edition. Addison Wesley. 2006.

Content History

Submissions
Submission Date	Submitter	Organization
2008-04-11 (CWE Draft 9, 2008-04-11)	CWE Content Team	MITRE
2008-04-11 (CWE Draft 9, 2008-04-11)
Modifications
Modification Date	Modifier	Organization
2023-06-29	CWE Content Team	MITRE
2023-06-29	updated Mapping_Notes, Research_Gaps
2023-04-27	CWE Content Team	MITRE
2023-04-27	updated Relationships, Time_of_Introduction
2023-01-31	CWE Content Team	MITRE
2023-01-31	updated Description, Potential_Mitigations
2021-07-20	CWE Content Team	MITRE
2021-07-20	updated Relationships
2020-12-10	CWE Content Team	MITRE
2020-12-10	updated Relationships
2020-08-20	CWE Content Team	MITRE
2020-08-20	updated Relationships
2020-02-24	CWE Content Team	MITRE
2020-02-24	updated Applicable_Platforms, Observed_Examples, Relationships, Type
2019-06-20	CWE Content Team	MITRE
2019-06-20	updated Related_Attack_Patterns, Relationships
2019-01-03	CWE Content Team	MITRE
2019-01-03	updated Relationships
2017-11-08	CWE Content Team	MITRE
2017-11-08	updated Taxonomy_Mappings
2017-01-19	CWE Content Team	MITRE
2017-01-19	updated Applicable_Platforms
2015-12-07	CWE Content Team	MITRE
2015-12-07	updated Relationships
2014-07-30	CWE Content Team	MITRE
2014-07-30	updated Relationships
2014-02-18	CWE Content Team	MITRE
2014-02-18	updated Relationships
2012-05-11	CWE Content Team	MITRE
2012-05-11	updated Demonstrative_Examples, References, Relationships
2011-09-13	CWE Content Team	MITRE
2011-09-13	updated Relationships, Taxonomy_Mappings
2011-06-01	CWE Content Team	MITRE
2011-06-01	updated Common_Consequences
2011-03-29	CWE Content Team	MITRE
2011-03-29	updated Relationships
2010-09-27	CWE Content Team	MITRE
2010-09-27	updated Potential_Mitigations
2010-06-21	CWE Content Team	MITRE
2010-06-21	updated Potential_Mitigations
2010-04-05	CWE Content Team	MITRE
2010-04-05	updated Detection_Factors, Potential_Mitigations, References
2010-02-16	CWE Content Team	MITRE
2010-02-16	updated Potential_Mitigations
2009-10-29	CWE Content Team	MITRE
2009-10-29	updated Demonstrative_Examples, Relationships
2009-07-27	CWE Content Team	MITRE
2009-07-27	updated Demonstrative_Examples, Related_Attack_Patterns
2009-05-27	CWE Content Team	MITRE
2009-05-27	updated Demonstrative_Examples
2009-03-10	CWE Content Team	MITRE
2009-03-10	updated Potential_Mitigations
2009-01-12	CWE Content Team	MITRE
2009-01-12	updated Applicable_Platforms, Common_Consequences, Demonstrative_Examples, Description, Likelihood_of_Exploit, Potential_Mitigations, Relationships
2008-11-24	CWE Content Team	MITRE
2008-11-24	updated Relationships, Taxonomy_Mappings
2008-10-14	CWE Content Team	MITRE
2008-10-14	updated Type
2008-09-08	CWE Content Team	MITRE
2008-09-08	updated Relationships
2008-07-01	Eric Dalci	Cigital
2008-07-01	updated Potential_Mitigations, Time_of_Introduction

Weakness ID: 131

View customized information:

Description

The product does not correctly calculate the size to be used when allocating a buffer, which could lead to a buffer overflow.

Common Consequences

Impact

Details

DoS: Crash, Exit, or Restart; Execute Unauthorized Code or Commands; Read Memory; Modify Memory

Scope: Integrity, Availability, Confidentiality

If the incorrect calculation is used in the context of memory allocation, then the software may create a buffer that is smaller or larger than expected. If the allocated buffer is smaller than expected, this could lead to an out-of-bounds read or write (CWE-119), possibly causing a crash, allowing arbitrary code execution, or exposing sensitive data.

Potential Mitigations

Phase(s)	Mitigation
Implementation	When allocating a buffer for the purpose of transforming, converting, or encoding an input, allocate enough memory to handle the largest possible encoding. For example, in a routine that converts "&" characters to "&" for HTML entity encoding, the output buffer needs to be at least 5 times as large as the input buffer.
Implementation	Understand the programming language's underlying representation and how it interacts with numeric calculation (CWE-681). Pay close attention to byte size discrepancies, precision, signed/unsigned distinctions, truncation, conversion and casting between types, "not-a-number" calculations, and how the language handles numbers that are too large or too small for its underlying representation. [REF-7] Also be careful to account for 32-bit, 64-bit, and other potential differences that may affect the numeric representation.
Implementation	Strategy: Input Validation Perform input validation on any numeric input by ensuring that it is within the expected range. Enforce that the input meets both the minimum and maximum requirements for the expected range.
Architecture and Design	For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.
Implementation	When processing structured incoming data containing a size field followed by raw data, identify and resolve any inconsistencies between the size field and the actual size of the data (CWE-130).
Implementation	When allocating memory that uses sentinels to mark the end of a data structure - such as NUL bytes in strings - make sure you also include the sentinel in your calculation of the total amount of memory that must be allocated.
Implementation	Replace unbounded copy functions with analogous functions that support length arguments, such as strcpy with strncpy. Create these if they are not available. Effectiveness: Moderate Note: This approach is still susceptible to calculation errors, including issues such as off-by-one errors (CWE-193) and incorrectly calculating buffer lengths (CWE-131). Additionally, this only addresses potential overflow issues. Resource consumption / exhaustion issues are still possible.
Implementation	Use sizeof() on the appropriate data type to avoid CWE-467.
Implementation	Use the appropriate type for the desired action. For example, in C/C++, only use unsigned types for values that could never be negative, such as height, width, or other numbers related to quantity. This will simplify validation and will reduce surprises related to unexpected casting.
Architecture and Design	Strategy: Libraries or Frameworks Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. Use libraries or frameworks that make it easier to handle numbers without unexpected consequences, or buffer allocation routines that automatically track buffer size. Examples include safe integer handling packages such as SafeInt (C++) or IntegerLib (C or C++). [REF-106]
Operation; Build and Compilation	Strategy: Environment Hardening Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index checking. D3-SFCV (Stack Frame Canary Validation) from D3FEND [REF-1334] discusses canary-based detection in detail. Effectiveness: Defense in Depth Note: This is not necessarily a complete solution, since these mechanisms only detect certain types of overflows. In addition, the result is still a denial of service, since the typical response is to exit the application.
Operation; Build and Compilation	Strategy: Environment Hardening Run or compile the software using features or extensions that randomly arrange the positions of a program's executable and libraries in memory. Because this makes the addresses unpredictable, it can prevent an attacker from reliably jumping to exploitable code. Examples include Address Space Layout Randomization (ASLR) [REF-58] [REF-60] and Position-Independent Executables (PIE) [REF-64]. Imported modules may be similarly realigned if their default memory addresses conflict with other modules, in a process known as "rebasing" (for Windows) and "prelinking" (for Linux) [REF-1332] using randomly generated addresses. ASLR for libraries cannot be used in conjunction with prelink since it would require relocating the libraries at run-time, defeating the whole purpose of prelinking. For more information on these techniques see D3-SAOR (Segment Address Offset Randomization) from D3FEND [REF-1335]. Effectiveness: Defense in Depth Note: These techniques do not provide a complete solution. For instance, exploits frequently use a bug that discloses memory addresses in order to maximize reliability of code execution [REF-1337]. It has also been shown that a side-channel attack can bypass ASLR [REF-1333]
Operation	Strategy: Environment Hardening Use a CPU and operating system that offers Data Execution Protection (using hardware NX or XD bits) or the equivalent techniques that simulate this feature in software, such as PaX [REF-60] [REF-61]. These techniques ensure that any instruction executed is exclusively at a memory address that is part of the code segment. For more information on these techniques see D3-PSEP (Process Segment Execution Prevention) from D3FEND [REF-1336]. Effectiveness: Defense in Depth Note: This is not a complete solution, since buffer overflows could be used to overwrite nearby variables to modify the software's state in dangerous ways. In addition, it cannot be used in cases in which self-modifying code is required. Finally, an attack could still cause a denial of service, since the typical response is to exit the application.
Implementation	Strategy: Compilation or Build Hardening Examine compiler warnings closely and eliminate problems with potential security implications, such as signed / unsigned mismatch in memory operations, or use of uninitialized variables. Even if the weakness is rarely exploitable, a single failure may lead to the compromise of the entire system.
Architecture and Design; Operation	Strategy: Environment Hardening Run your code using the lowest privileges that are required to accomplish the necessary tasks [REF-76]. If possible, create isolated accounts with limited privileges that are only used for a single task. That way, a successful attack will not immediately give the attacker access to the rest of the software or its environment. For example, database applications rarely need to run as the database administrator, especially in day-to-day operations.
Architecture and Design; Operation	Strategy: Sandbox or Jail Run the code in a "jail" or similar sandbox environment that enforces strict boundaries between the process and the operating system. This may effectively restrict which files can be accessed in a particular directory or which commands can be executed by the software. OS-level examples include the Unix chroot jail, AppArmor, and SELinux. In general, managed code may provide some protection. For example, java.io.FilePermission in the Java SecurityManager allows the software to specify restrictions on file operations. This may not be a feasible solution, and it only limits the impact to the operating system; the rest of the application may still be subject to compromise. Be careful to avoid CWE-243 and other weaknesses related to jails. Effectiveness: Limited Note: The effectiveness of this mitigation depends on the prevention capabilities of the specific sandbox or jail being used and might only help to reduce the scope of an attack, such as restricting the attacker to certain system calls or limiting the portion of the file system that can be accessed.

Relationships

Relevant to the view "Research Concepts" (View-1000)

Nature	Type	ID	Name
ChildOf	Pillar - a weakness that is the most abstract type of weakness and represents a theme for all class/base/variant weaknesses related to it. A Pillar is different from a Category as a Pillar is still technically a type of weakness that describes a mistake, while a Category represents a common characteristic used to group related things.	682	Incorrect Calculation
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	467	Use of sizeof() on a Pointer Type
CanPrecede	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	119	Improper Restriction of Operations within the Bounds of a Memory Buffer

Relevant to the view "Software Development" (View-699)

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1218	Memory Buffer Errors

Relevant to the view "Weaknesses for Simplified Mapping of Published Vulnerabilities" (View-1003)

Nature	Type	ID	Name
ChildOf	Pillar - a weakness that is the most abstract type of weakness and represents a theme for all class/base/variant weaknesses related to it. A Pillar is different from a Category as a Pillar is still technically a type of weakness that describes a mistake, while a Category represents a common characteristic used to group related things.	682	Incorrect Calculation

Relevant to the view "CISQ Quality Measures (2020)" (View-1305)

Nature	Type	ID	Name
ChildOf	Pillar - a weakness that is the most abstract type of weakness and represents a theme for all class/base/variant weaknesses related to it. A Pillar is different from a Category as a Pillar is still technically a type of weakness that describes a mistake, while a Category represents a common characteristic used to group related things.	682	Incorrect Calculation

Relevant to the view "CISQ Data Protection Measures" (View-1340)

Nature	Type	ID	Name
ChildOf	Pillar - a weakness that is the most abstract type of weakness and represents a theme for all class/base/variant weaknesses related to it. A Pillar is different from a Category as a Pillar is still technically a type of weakness that describes a mistake, while a Category represents a common characteristic used to group related things.	682	Incorrect Calculation

Modes Of Introduction

Phase	Note
Implementation

Applicable Platforms

Languages

C (Undetermined Prevalence)

C++ (Undetermined Prevalence)

Likelihood Of Exploit

High

Demonstrative Examples

Example 1

The following code allocates memory for a maximum number of widgets. It then gets a user-specified number of widgets, making sure that the user does not request too many. It then initializes the elements of the array using InitializeWidget(). Because the number of widgets can vary for each request, the code inserts a NULL pointer to signify the location of the last widget.

(bad code)

Example Language: C

int i;
unsigned int numWidgets;
Widget **WidgetList;

numWidgets = GetUntrustedSizeValue();
if ((numWidgets == 0) || (numWidgets > MAX_NUM_WIDGETS)) {

ExitError("Incorrect number of widgets requested!");

}
WidgetList = (Widget **)malloc(numWidgets * sizeof(Widget *));
printf("WidgetList ptr=%p\n", WidgetList);
for(i=0; i<numWidgets; i++) {

WidgetList[i] = InitializeWidget();

}
WidgetList[numWidgets] = NULL;
showWidgets(WidgetList);

However, this code contains an off-by-one calculation error (CWE-193). It allocates exactly enough space to contain the specified number of widgets, but it does not include the space for the NULL pointer. As a result, the allocated buffer is smaller than it is supposed to be (CWE-131). So if the user ever requests MAX_NUM_WIDGETS, there is an out-of-bounds write (CWE-787) when the NULL is assigned. Depending on the environment and compilation settings, this could cause memory corruption.

Example 2

The following image processing code allocates a table for images.

(bad code)

Example Language: C

img_t table_ptr; /*struct containing img data, 10kB each*/
int num_imgs;
...
num_imgs = get_num_imgs();
table_ptr = (img_t*)malloc(sizeof(img_t)*num_imgs);
...

Example 3

This example applies an encoding procedure to an input string and stores it into a buffer.

(bad code)

Example Language: C

char * copy_input(char *user_supplied_string){

int i, dst_index;
char *dst_buf = (char*)malloc(4*sizeof(char) * MAX_SIZE);
if ( MAX_SIZE <= strlen(user_supplied_string) ){

die("user string too long, die evil hacker!");

}
dst_index = 0;
for ( i = 0; i < strlen(user_supplied_string); i++ ){

if( '&' == user_supplied_string[i] ){

dst_buf[dst_index++] = '&';
dst_buf[dst_index++] = 'a';
dst_buf[dst_index++] = 'm';
dst_buf[dst_index++] = 'p';
dst_buf[dst_index++] = ';';

}
else if ('<' == user_supplied_string[i] ){

/* encode to < */

}
else dst_buf[dst_index++] = user_supplied_string[i];

}
return dst_buf;

}

Example 4

The following code is intended to read an incoming packet from a socket and extract one or more headers.

(bad code)

Example Language: C

DataPacket *packet;
int numHeaders;
PacketHeader *headers;

sock=AcceptSocketConnection();
ReadPacket(packet, sock);
numHeaders =packet->headers;

if (numHeaders > 100) {

ExitError("too many headers!");

}
headers = malloc(numHeaders * sizeof(PacketHeader);
ParsePacketHeaders(packet, headers);

The code performs a check to make sure that the packet does not contain too many headers. However, numHeaders is defined as a signed int, so it could be negative. If the incoming packet specifies a value such as -3, then the malloc calculation will generate a negative number (say, -300 if each header can be a maximum of 100 bytes). When this result is provided to malloc(), it is first converted to a size_t type. This conversion then produces a large value such as 4294966996, which may cause malloc() to fail or to allocate an extremely large amount of memory (CWE-195). With the appropriate negative numbers, an attacker could trick malloc() into using a very small positive number, which then allocates a buffer that is much smaller than expected, potentially leading to a buffer overflow.

Example 5

The following code attempts to save three different identification numbers into an array. The array is allocated from memory using a call to malloc().

(bad code)

Example Language: C

int *id_sequence;

/* Allocate space for an array of three ids. */

id_sequence = (int*) malloc(3);
if (id_sequence == NULL) exit(1);

/* Populate the id array. */

id_sequence[0] = 13579;
id_sequence[1] = 24680;
id_sequence[2] = 97531;

The problem with the code above is the value of the size parameter used during the malloc() call. It uses a value of '3' which by definition results in a buffer of three bytes to be created. However the intention was to create a buffer that holds three ints, and in C, each int requires 4 bytes worth of memory, so an array of 12 bytes is needed, 4 bytes for each int. Executing the above code could result in a buffer overflow as 12 bytes of data is being saved into 3 bytes worth of allocated space. The overflow would occur during the assignment of id_sequence[0] and would continue with the assignment of id_sequence[1] and id_sequence[2].

The malloc() call could have used '3*sizeof(int)' as the value for the size parameter in order to allocate the correct amount of space required to store the three ints.

Selected Observed Examples

Reference	Description
CVE-2025-27363	Font rendering library does not properly handle assigning a signed short value to an unsigned long (CWE-195), leading to an integer wraparound (CWE-190), causing too small of a buffer (CWE-131), leading to an out-of-bounds write (CWE-787).
CVE-2020-17087	Chain: integer truncation (CWE-197) causes small buffer allocation (CWE-131) leading to out-of-bounds write (CWE-787) in kernel pool, as exploited in the wild per CISA KEV.
CVE-2004-1363	substitution overflow: buffer overflow using environment variables that are expanded after the length check is performed
CVE-2004-0747	substitution overflow: buffer overflow using expansion of environment variables
CVE-2005-2103	substitution overflow: buffer overflow using a large number of substitution strings
CVE-2005-3120	transformation overflow: product adds extra escape characters to incoming data, but does not account for them in the buffer length
CVE-2003-0899	transformation overflow: buffer overflow when expanding ">" to ">", etc.
CVE-2001-0334	expansion overflow: buffer overflow using wildcards
CVE-2001-0248	expansion overflow: long pathname + glob = overflow
CVE-2001-0249	expansion overflow: long pathname + glob = overflow
CVE-2002-0184	special characters in argument are not properly expanded
CVE-2004-0434	small length value leads to heap overflow
CVE-2002-1347	multiple variants
CVE-2005-0490	needs closer investigation, but probably expansion-based
CVE-2004-0940	needs closer investigation, but probably expansion-based
CVE-2008-0599	Chain: Language interpreter calculates wrong buffer size (CWE-131) by using "size = ptr ? X : Y" instead of "size = (ptr ? X : Y)" expression.

Detection Methods

Method	Details
Automated Static Analysis	This weakness can often be detected using automated static analysis tools. Many modern tools use data flow analysis or constraint-based techniques to minimize the number of false positives. Automated static analysis generally does not account for environmental considerations when reporting potential errors in buffer calculations. This can make it difficult for users to determine which warnings should be investigated first. For example, an analysis tool might report buffer overflows that originate from command line arguments in a program that is not expected to run with setuid or other special privileges. Effectiveness: High Note:Detection techniques for buffer-related errors are more mature than for most other weakness types.
Automated Dynamic Analysis	This weakness can be detected using dynamic tools and techniques that interact with the software using large test suites with many diverse inputs, such as fuzz testing (fuzzing), robustness testing, and fault injection. The software's operation may slow down, but it should not become unstable, crash, or generate incorrect results. Effectiveness: Moderate Note:Without visibility into the code, black box methods may not be able to sufficiently distinguish this weakness from others, requiring follow-up manual methods to diagnose the underlying problem.
Manual Analysis	Manual analysis can be useful for finding this weakness, but it might not achieve desired code coverage within limited time constraints. This becomes difficult for weaknesses that must be considered for all inputs, since the attack surface can be too large.
Manual Analysis	This weakness can be detected using tools and techniques that require manual (human) analysis, such as penetration testing, threat modeling, and interactive tools that allow the tester to record and modify an active session. Specifically, manual static analysis is useful for evaluating the correctness of allocation calculations. This can be useful for detecting overflow conditions (CWE-190) or similar weaknesses that might have serious security impacts on the program. Effectiveness: High Note:These may be more effective than strictly automated techniques. This is especially the case with weaknesses that are related to design and business rules.
Automated Static Analysis - Binary or Bytecode	According to SOAR, the following detection techniques may be useful: Highly cost effective: Bytecode Weakness Analysis - including disassembler + source code weakness analysis Binary Weakness Analysis - including disassembler + source code weakness analysis Effectiveness: High
Manual Static Analysis - Binary or Bytecode	According to SOAR, the following detection techniques may be useful: Cost effective for partial coverage: Binary / Bytecode disassembler - then use manual analysis for vulnerabilities & anomalies Effectiveness: SOAR Partial
Manual Static Analysis - Source Code	According to SOAR, the following detection techniques may be useful: Cost effective for partial coverage: Focused Manual Spotcheck - Focused manual analysis of source Manual Source Code Review (not inspections) Effectiveness: SOAR Partial
Automated Static Analysis - Source Code	According to SOAR, the following detection techniques may be useful: Highly cost effective: Source code Weakness Analyzer Context-configured Source Code Weakness Analyzer Cost effective for partial coverage: Source Code Quality Analyzer Effectiveness: High
Architecture or Design Review	According to SOAR, the following detection techniques may be useful: Highly cost effective: Formal Methods / Correct-By-Construction Cost effective for partial coverage: Inspection (IEEE 1028 standard) (can apply to requirements, design, source code, etc.) Effectiveness: High

Memberships

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	742	CERT C Secure Coding Standard (2008) Chapter 9 - Memory Management (MEM)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	802	2010 Top 25 - Risky Resource Management
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	865	2011 Top 25 - Risky Resource Management
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	876	CERT C++ Secure Coding Section 08 - Memory Management (MEM)
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	884	CWE Cross-section
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	974	SFP Secondary Cluster: Incorrect Buffer Length Computation
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1158	SEI CERT C Coding Standard - Guidelines 04. Integers (INT)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1162	SEI CERT C Coding Standard - Guidelines 08. Memory Management (MEM)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1399	Comprehensive Categorization: Memory Safety

Vulnerability Mapping Notes

Usage	ALLOWED (this CWE ID may be used to map to real-world vulnerabilities)
Reason	Acceptable-Use
Rationale	This CWE entry is at the Base level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.
Comments	Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction.

Notes

Maintenance

This is a broad category. Some examples include:

simple math errors,
incorrectly updating parallel counters,
not accounting for size differences when "transforming" one input to another format (e.g. URL canonicalization or other transformation that can generate a result that's larger than the original input, i.e. "expansion").

This level of detail is rarely available in public reports, so it is difficult to find good examples.

Maintenance

This weakness may be a composite or a chain. It also may contain layering or perspective differences.

This issue may be associated with many different types of incorrect calculations (CWE-682), although the integer overflow (CWE-190) is probably the most prevalent. This can be primary to resource consumption problems (CWE-400), including uncontrolled memory allocation (CWE-789). However, its relationship with out-of-bounds buffer access (CWE-119) must also be considered.

Taxonomy Mappings

Mapped Taxonomy Name	Node ID	Fit	Mapped Node Name
PLOVER			Other length calculation error
CERT C Secure Coding	INT30-C	Imprecise	Ensure that unsigned integer operations do not wrap
CERT C Secure Coding	MEM35-C	CWE More Abstract	Allocate sufficient memory for an object

Related Attack Patterns

CAPEC-ID	Attack Pattern Name
CAPEC-100	Overflow Buffers
CAPEC-47	Buffer Overflow via Parameter Expansion

References

[REF-106]	David LeBlanc and Niels Dekker. "SafeInt". <http://safeint.codeplex.com/>.
[REF-107]	Jason Lam. "Top 25 Series - Rank 18 - Incorrect Calculation of Buffer Size". SANS Software Security Institute. 2010-03-19. <http://software-security.sans.org/blog/2010/03/19/top-25-series-rank-18-incorrect-calculation-of-buffer-size>.
[REF-58]	Michael Howard. "Address Space Layout Randomization in Windows Vista". <https://learn.microsoft.com/en-us/archive/blogs/michael_howard/address-space-layout-randomization-in-windows-vista>. (URL validated: 2023-04-07)
[REF-61]	Microsoft. "Understanding DEP as a mitigation technology part 1". <https://msrc.microsoft.com/blog/2009/06/understanding-dep-as-a-mitigation-technology-part-1/>. (URL validated: 2023-04-07)
[REF-60]	"PaX". <https://en.wikipedia.org/wiki/Executable_space_protection#PaX>. (URL validated: 2023-04-07)
[REF-76]	Sean Barnum and Michael Gegick. "Least Privilege". 2005-09-14. <https://web.archive.org/web/20211209014121/https://www.cisa.gov/uscert/bsi/articles/knowledge/principles/least-privilege>. (URL validated: 2023-04-07)
[REF-7]	Michael Howard and David LeBlanc. "Writing Secure Code". Chapter 20, "Integer Overflows" Page 620. 2nd Edition. Microsoft Press. 2002-12-04. <https://www.microsoftpressstore.com/store/writing-secure-code-9780735617223>.
[REF-44]	Michael Howard, David LeBlanc and John Viega. "24 Deadly Sins of Software Security". "Sin 5: Buffer Overruns." Page 89. McGraw-Hill. 2010.
[REF-62]	Mark Dowd, John McDonald and Justin Schuh. "The Art of Software Security Assessment". Chapter 8, "Incrementing Pointers Incorrectly", Page 401. 1st Edition. Addison Wesley. 2006.
[REF-64]	Grant Murphy. "Position Independent Executables (PIE)". Red Hat. 2012-11-28. <https://www.redhat.com/en/blog/position-independent-executables-pie>. (URL validated: 2023-04-07)
[REF-1332]	John Richard Moser. "Prelink and address space randomization". 2006-07-05. <https://lwn.net/Articles/190139/>. (URL validated: 2023-04-26)
[REF-1333]	Dmitry Evtyushkin, Dmitry Ponomarev, Nael Abu-Ghazaleh. "Jump Over ASLR: Attacking Branch Predictors to Bypass ASLR". 2016. <http://www.cs.ucr.edu/~nael/pubs/micro16.pdf>. (URL validated: 2023-04-26)
[REF-1334]	D3FEND. "Stack Frame Canary Validation (D3-SFCV)". 2023. <https://d3fend.mitre.org/technique/d3f:StackFrameCanaryValidation/>. (URL validated: 2023-04-26)
[REF-1335]	D3FEND. "Segment Address Offset Randomization (D3-SAOR)". 2023. <https://d3fend.mitre.org/technique/d3f:SegmentAddressOffsetRandomization/>. (URL validated: 2023-04-26)
[REF-1336]	D3FEND. "Process Segment Execution Prevention (D3-PSEP)". 2023. <https://d3fend.mitre.org/technique/d3f:ProcessSegmentExecutionPrevention/>. (URL validated: 2023-04-26)
[REF-1337]	Alexander Sotirov and Mark Dowd. "Bypassing Browser Memory Protections: Setting back browser security by 10 years". Memory information leaks. 2008. <https://www.blackhat.com/presentations/bh-usa-08/Sotirov_Dowd/bh08-sotirov-dowd.pdf>. (URL validated: 2023-04-26)

Content History

Submissions
Submission Date	Submitter	Organization
2006-07-19 (CWE Draft 3, 2006-07-19)	PLOVER
2006-07-19 (CWE Draft 3, 2006-07-19)
Modifications
Modification Date	Modifier	Organization
2025-04-03 (CWE 4.17, 2025-04-03)	CWE Content Team	MITRE
2025-04-03 (CWE 4.17, 2025-04-03)	updated Observed_Examples
2023-06-29	CWE Content Team	MITRE
2023-06-29	updated Mapping_Notes
2023-04-27	CWE Content Team	MITRE
2023-04-27	updated Potential_Mitigations, References, Relationships
2023-01-31	CWE Content Team	MITRE
2023-01-31	updated Description
2022-10-13	CWE Content Team	MITRE
2022-10-13	updated References
2022-06-28	CWE Content Team	MITRE
2022-06-28	updated Observed_Examples
2021-03-15	CWE Content Team	MITRE
2021-03-15	updated Demonstrative_Examples, Potential_Mitigations
2020-12-10	CWE Content Team	MITRE
2020-12-10	updated Relationships
2020-08-20	CWE Content Team	MITRE
2020-08-20	updated Relationships
2020-02-24	CWE Content Team	MITRE
2020-02-24	updated Relationships
2019-06-20	CWE Content Team	MITRE
2019-06-20	updated Relationships
2019-01-03	CWE Content Team	MITRE
2019-01-03	updated Relationships
2018-03-27	CWE Content Team	MITRE
2018-03-27	updated References
2017-11-08	CWE Content Team	MITRE
2017-11-08	updated Likelihood_of_Exploit, References, Taxonomy_Mappings
2014-07-30	CWE Content Team	MITRE
2014-07-30	updated Detection_Factors, Relationships
2014-02-18	CWE Content Team	MITRE
2014-02-18	updated Potential_Mitigations, References
2013-07-17	CWE Content Team	MITRE
2013-07-17	updated References
2013-02-21	CWE Content Team	MITRE
2013-02-21	updated Demonstrative_Examples
2012-10-30	CWE Content Team	MITRE
2012-10-30	updated Potential_Mitigations
2012-05-11	CWE Content Team	MITRE
2012-05-11	updated Demonstrative_Examples, Potential_Mitigations, References, Relationships
2011-09-13	CWE Content Team	MITRE
2011-09-13	updated Potential_Mitigations, References, Relationships, Taxonomy_Mappings
2011-06-27	CWE Content Team	MITRE
2011-06-27	updated Relationships
2011-06-01	CWE Content Team	MITRE
2011-06-01	updated Common_Consequences
2011-03-29	CWE Content Team	MITRE
2011-03-29	updated Maintenance_Notes
2010-12-13	CWE Content Team	MITRE
2010-12-13	updated Potential_Mitigations
2010-09-27	CWE Content Team	MITRE
2010-09-27	updated Potential_Mitigations
2010-06-21	CWE Content Team	MITRE
2010-06-21	updated Common_Consequences, Detection_Factors, Potential_Mitigations, References
2010-04-05	CWE Content Team	MITRE
2010-04-05	updated Detection_Factors, Potential_Mitigations, References, Related_Attack_Patterns
2010-02-16	CWE Content Team	MITRE
2010-02-16	updated Common_Consequences, Demonstrative_Examples, Detection_Factors, Maintenance_Notes, Potential_Mitigations, Related_Attack_Patterns, Relationships
2009-12-28	CWE Content Team	MITRE
2009-12-28	updated Demonstrative_Examples, Likelihood_of_Exploit, Observed_Examples, Potential_Mitigations
2008-11-24	CWE Content Team	MITRE
2008-11-24	updated Relationships, Taxonomy_Mappings
2008-10-14	CWE Content Team	MITRE
2008-10-14	updated Relationships
2008-09-08	CWE Content Team	MITRE
2008-09-08	updated Applicable_Platforms, Maintenance_Notes, Relationships, Taxonomy_Mappings, Type
2008-07-01	Eric Dalci	Cigital
2008-07-01	updated Potential_Mitigations, Time_of_Introduction
Previous Entry Names
Change Date	Previous Entry Name
2008-01-30	Other Length Calculation Error

Weakness ID: 681

View customized information:

Description

Common Consequences

Impact	Details
Unexpected State; Quality Degradation	Scope: Other, Integrity The program could wind up using the wrong number and generate incorrect results. If the number is used to allocate resources or make a security decision, then this could introduce a vulnerability.

Potential Mitigations

Phase(s)	Mitigation
Implementation	Avoid making conversion between numeric types. Always check for the allowed ranges.

Relationships

Relevant to the view "Research Concepts" (View-1000)

Nature	Type	ID	Name
ChildOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	704	Incorrect Type Conversion or Cast
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	192	Integer Coercion Error
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	194	Unexpected Sign Extension
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	195	Signed to Unsigned Conversion Error
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	196	Unsigned to Signed Conversion Error
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	197	Numeric Truncation Error
CanPrecede	Pillar - a weakness that is the most abstract type of weakness and represents a theme for all class/base/variant weaknesses related to it. A Pillar is different from a Category as a Pillar is still technically a type of weakness that describes a mistake, while a Category represents a common characteristic used to group related things.	682	Incorrect Calculation

Relevant to the view "Software Development" (View-699)

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	136	Type Errors
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	189	Numeric Errors

Relevant to the view "Weaknesses for Simplified Mapping of Published Vulnerabilities" (View-1003)

Nature	Type	ID	Name
ChildOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	704	Incorrect Type Conversion or Cast

Relevant to the view "CISQ Quality Measures (2020)" (View-1305)

Nature	Type	ID	Name
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	194	Unexpected Sign Extension
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	195	Signed to Unsigned Conversion Error
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	196	Unsigned to Signed Conversion Error
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	197	Numeric Truncation Error

Relevant to the view "CISQ Data Protection Measures" (View-1340)

Nature	Type	ID	Name
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	194	Unexpected Sign Extension
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	195	Signed to Unsigned Conversion Error
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	196	Unsigned to Signed Conversion Error
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	197	Numeric Truncation Error

Modes Of Introduction

Phase	Note
Implementation

Applicable Platforms

Languages

C (Undetermined Prevalence)

Class: Not Language-Specific (Undetermined Prevalence)

Likelihood Of Exploit

High

Demonstrative Examples

Example 1

In the following Java example, a float literal is cast to an integer, thus causing a loss of precision.

(bad code)

Example Language: Java

int i = (int) 33457.8f;

Example 2

This code adds a float and an integer together, casting the result to an integer.

(bad code)

Example Language: PHP

$floatVal = 1.8345;
$intVal = 3;
$result = (int)$floatVal + $intVal;

Normally, PHP will preserve the precision of this operation, making $result = 4.8345. After the cast to int, it is reasonable to expect PHP to follow rounding convention and set $result = 5. However, the explicit cast to int always rounds DOWN, so the final value of $result is 4. This behavior may have unintended consequences.

Example 3

In this example the variable amount can hold a negative value when it is returned. Because the function is declared to return an unsigned int, amount will be implicitly converted to unsigned.

(bad code)

Example Language: C

unsigned int readdata () {

int amount = 0;
...
if (result == ERROR)
amount = -1;
...
return amount;

}

If the error condition in the code above is met, then the return value of readdata() will be 4,294,967,295 on a system that uses 32-bit integers.

Example 4

In this example, depending on the return value of accecssmainframe(), the variable amount can hold a negative value when it is returned. Because the function is declared to return an unsigned value, amount will be implicitly cast to an unsigned number.

(bad code)

Example Language: C

unsigned int readdata () {

int amount = 0;
...
amount = accessmainframe();
...
return amount;

}

If the return value of accessmainframe() is -1, then the return value of readdata() will be 4,294,967,295 on a system that uses 32-bit integers.

Selected Observed Examples

Reference	Description
CVE-2022-2639	Chain: integer coercion error (CWE-192) prevents a return value from indicating an error, leading to out-of-bounds write (CWE-787)
CVE-2021-43537	Chain: in a web browser, an unsigned 64-bit integer is forcibly cast to a 32-bit integer (CWE-681) and potentially leading to an integer overflow (CWE-190). If an integer overflow occurs, this can cause heap memory corruption (CWE-122)
CVE-2007-4268	Chain: integer signedness error (CWE-195) passes signed comparison, leading to heap overflow (CWE-122)
CVE-2007-4988	Chain: signed short width value in image processor is sign extended during conversion to unsigned int, which leads to integer overflow and heap-based buffer overflow.
CVE-2009-0231	Integer truncation of length value leads to heap-based buffer overflow.
CVE-2008-3282	Size of a particular type changes for 64-bit platforms, leading to an integer truncation in document processor causes incorrect index to be generated.

Memberships

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	738	CERT C Secure Coding Standard (2008) Chapter 5 - Integers (INT)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	739	CERT C Secure Coding Standard (2008) Chapter 6 - Floating Point (FLP)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	808	2010 Top 25 - Weaknesses On the Cusp
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	848	The CERT Oracle Secure Coding Standard for Java (2011) Chapter 5 - Numeric Types and Operations (NUM)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	867	2011 Top 25 - Weaknesses On the Cusp
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	872	CERT C++ Secure Coding Section 04 - Integers (INT)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	873	CERT C++ Secure Coding Section 05 - Floating Point Arithmetic (FLP)
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	884	CWE Cross-section
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	998	SFP Secondary Cluster: Glitch in Computation
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1131	CISQ Quality Measures (2016) - Security
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1137	SEI CERT Oracle Secure Coding Standard for Java - Guidelines 03. Numeric Types and Operations (NUM)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1158	SEI CERT C Coding Standard - Guidelines 04. Integers (INT)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1159	SEI CERT C Coding Standard - Guidelines 05. Floating Point (FLP)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1306	CISQ Quality Measures - Reliability
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1308	CISQ Quality Measures - Security
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1340	CISQ Data Protection Measures
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1416	Comprehensive Categorization: Resource Lifecycle Management

Vulnerability Mapping Notes

Usage	ALLOWED (this CWE ID may be used to map to real-world vulnerabilities)
Reason	Acceptable-Use
Rationale	This CWE entry is at the Base level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.
Comments	Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction.

Taxonomy Mappings

Mapped Taxonomy Name	Node ID	Fit	Mapped Node Name
CERT C Secure Coding	FLP34-C	CWE More Abstract	Ensure that floating point conversions are within range of the new type
CERT C Secure Coding	INT15-C		Use intmax_t or uintmax_t for formatted IO on programmer-defined integer types
CERT C Secure Coding	INT31-C	CWE More Abstract	Ensure that integer conversions do not result in lost or misinterpreted data
CERT C Secure Coding	INT35-C		Evaluate integer expressions in a larger size before comparing or assigning to that size
The CERT Oracle Secure Coding Standard for Java (2011)	NUM12-J		Ensure conversions of numeric types to narrower types do not result in lost or misinterpreted data
Software Fault Patterns	SFP1		Glitch in computation
OMG ASCSM	ASCSM-CWE-681

References

[REF-962]

Object Management Group (OMG). "Automated Source Code Security Measure (ASCSM)". ASCSM-CWE-681. 2016-01.
<http://www.omg.org/spec/ASCSM/1.0/>.

Content History

Submissions
Submission Date	Submitter	Organization
2008-04-11 (CWE Draft 9, 2008-04-11)	CWE Community
2008-04-11 (CWE Draft 9, 2008-04-11)	Submitted by members of the CWE community to extend early CWE versions
Modifications
Modification Date	Modifier	Organization
2025-04-03 (CWE 4.17, 2025-04-03)	CWE Content Team	MITRE
2025-04-03 (CWE 4.17, 2025-04-03)	updated Applicable_Platforms
2024-02-29 (CWE 4.14, 2024-02-29)	CWE Content Team	MITRE
2024-02-29 (CWE 4.14, 2024-02-29)	updated Observed_Examples
2023-10-26	CWE Content Team	MITRE
2023-10-26	updated Observed_Examples
2023-06-29	CWE Content Team	MITRE
2023-06-29	updated Mapping_Notes
2023-04-27	CWE Content Team	MITRE
2023-04-27	updated Relationships
2021-03-15	CWE Content Team	MITRE
2021-03-15	updated Relationships
2020-12-10	CWE Content Team	MITRE
2020-12-10	updated Relationships
2020-08-20	CWE Content Team	MITRE
2020-08-20	updated Relationships
2020-02-24	CWE Content Team	MITRE
2020-02-24	updated Relationships
2019-06-20	CWE Content Team	MITRE
2019-06-20	updated Relationships, Type
2019-01-03	CWE Content Team	MITRE
2019-01-03	updated References, Relationships, Taxonomy_Mappings
2017-11-08	CWE Content Team	MITRE
2017-11-08	updated Likelihood_of_Exploit, Observed_Examples, Taxonomy_Mappings, Type
2014-07-30	CWE Content Team	MITRE
2014-07-30	updated Relationships, Taxonomy_Mappings
2012-05-11	CWE Content Team	MITRE
2012-05-11	updated Demonstrative_Examples, References, Relationships, Taxonomy_Mappings
2011-09-13	CWE Content Team	MITRE
2011-09-13	updated Relationships, Taxonomy_Mappings
2011-06-27	CWE Content Team	MITRE
2011-06-27	updated Common_Consequences, Observed_Examples, Relationships
2011-06-01	CWE Content Team	MITRE
2011-06-01	updated Common_Consequences, Relationships, Taxonomy_Mappings
2011-03-29	CWE Content Team	MITRE
2011-03-29	updated Demonstrative_Examples
2010-02-16	CWE Content Team	MITRE
2010-02-16	updated Relationships
2009-12-28	CWE Content Team	MITRE
2009-12-28	updated Applicable_Platforms, Likelihood_of_Exploit, Potential_Mitigations
2008-11-24	CWE Content Team	MITRE
2008-11-24	updated Description, Relationships, Taxonomy_Mappings
2008-09-08	CWE Content Team	MITRE
2008-09-08	updated Relationships
2008-07-01	Eric Dalci	Cigital
2008-07-01	updated Potential_Mitigations, Time_of_Introduction
2008-07-01	Sean Eidemiller	Cigital
2008-07-01	added/updated demonstrative examples

Weakness ID: 732

Vulnerability Mapping: ALLOWED This CWE ID could be used to map to real-world vulnerabilities in limited situations requiring careful review (with careful review of mapping notes)
Abstraction: Class Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.

View customized information:

Description

The product specifies permissions for a security-critical resource in a way that allows that resource to be read or modified by unintended actors.

Extended Description

When a resource is given a permission setting that provides access to a wider range of actors than required, it could lead to the exposure of sensitive information, or the modification of that resource by unintended parties. This is especially dangerous when the resource is related to program configuration, execution, or sensitive user data. For example, consider a misconfigured storage account for the cloud that can be read or written by a public or anonymous user.

Common Consequences

Impact	Details
Read Application Data; Read Files or Directories	Scope: Confidentiality An attacker may be able to read sensitive information from the associated resource, such as credentials or configuration information stored in a file.
Gain Privileges or Assume Identity	Scope: Access Control An attacker may be able to modify critical properties of the associated resource to gain privileges, such as replacing a world-writable executable with a Trojan horse.
Modify Application Data; Other	Scope: Integrity, Other An attacker may be able to destroy or corrupt critical data in the associated resource, such as deletion of records from a database.

Potential Mitigations

Phase(s)	Mitigation
Implementation	When using a critical resource such as a configuration file, check to see if the resource has insecure permissions (such as being modifiable by any regular user) [REF-62], and generate an error or even exit the software if there is a possibility that the resource could have been modified by an unauthorized party.
Architecture and Design	Divide the software into anonymous, normal, privileged, and administrative areas. Reduce the attack surface by carefully defining distinct user groups, privileges, and/or roles. Map these against data, functionality, and the related resources. Then set the permissions accordingly. This will allow you to maintain more fine-grained control over your resources. [REF-207] Effectiveness: Moderate Note: This can be an effective strategy. However, in practice, it may be difficult or time consuming to define these areas when there are many different resources or user types, or if the applications features change rapidly.
Architecture and Design; Operation	Strategy: Sandbox or Jail Run the code in a "jail" or similar sandbox environment that enforces strict boundaries between the process and the operating system. This may effectively restrict which files can be accessed in a particular directory or which commands can be executed by the software. OS-level examples include the Unix chroot jail, AppArmor, and SELinux. In general, managed code may provide some protection. For example, java.io.FilePermission in the Java SecurityManager allows the software to specify restrictions on file operations. This may not be a feasible solution, and it only limits the impact to the operating system; the rest of the application may still be subject to compromise. Be careful to avoid CWE-243 and other weaknesses related to jails. Effectiveness: Limited Note: The effectiveness of this mitigation depends on the prevention capabilities of the specific sandbox or jail being used and might only help to reduce the scope of an attack, such as restricting the attacker to certain system calls or limiting the portion of the file system that can be accessed.
Implementation; Installation	During program startup, explicitly set the default permissions or umask to the most restrictive setting possible. Also set the appropriate permissions during program installation. This will prevent you from inheriting insecure permissions from any user who installs or runs the program. Effectiveness: High
System Configuration	For all configuration files, executables, and libraries, make sure that they are only readable and writable by the software's administrator. Effectiveness: High
Documentation	Do not suggest insecure configuration changes in documentation, especially if those configurations can extend to resources and other programs that are outside the scope of the application.
Installation	Do not assume that a system administrator will manually change the configuration to the settings that are recommended in the software's manual.
Operation; System Configuration	Strategy: Environment Hardening Ensure that the software runs properly under the United States Government Configuration Baseline (USGCB) [REF-199] or an equivalent hardening configuration guide, which many organizations use to limit the attack surface and potential risk of deployed software.
Implementation; System Configuration; Operation	When storing data in the cloud (e.g., S3 buckets, Azure blobs, Google Cloud Storage, etc.), use the provider's controls to disable public access.

Relationships

Relevant to the view "Research Concepts" (View-1000)

Nature	Type	ID	Name
ChildOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	285	Improper Authorization
ChildOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	668	Exposure of Resource to Wrong Sphere
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	276	Incorrect Default Permissions
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	277	Insecure Inherited Permissions
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	278	Insecure Preserved Inherited Permissions
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	279	Incorrect Execution-Assigned Permissions
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	281	Improper Preservation of Permissions
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	766	Critical Data Element Declared Public
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	1004	Sensitive Cookie Without 'HttpOnly' Flag

Relevant to the view "Weaknesses for Simplified Mapping of Published Vulnerabilities" (View-1003)

Nature	Type	ID	Name
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1003	Weaknesses for Simplified Mapping of Published Vulnerabilities
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	276	Incorrect Default Permissions
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	281	Improper Preservation of Permissions

Relevant to the view "Architectural Concepts" (View-1008)

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1011	Authorize Actors

Modes Of Introduction

Phase	Note
Architecture and Design
Implementation	REALIZATION: This weakness is caused during implementation of an architectural security tactic. The developer might make certain assumptions about the environment in which the product operates - e.g., that the software is running on a single-user system, or the software is only accessible to trusted administrators. When the software is running in a different environment, the permissions become a problem.
Installation	The developer may set loose permissions in order to minimize problems when the user first runs the program, then create documentation stating that permissions should be tightened. Since system administrators and users do not always read the documentation, this can result in insecure permissions being left unchanged.
Operation

Applicable Platforms

Languages	Class: Not Language-Specific (Undetermined Prevalence)
Technologies	Class: Not Technology-Specific (Undetermined Prevalence) Class: Cloud Computing (Often Prevalent)

Likelihood Of Exploit

High

Demonstrative Examples

Example 1

The following code sets the umask of the process to 0 before creating a file and writing "Hello world" into the file.

(bad code)

Example Language: C

#define OUTFILE "hello.out"

umask(0);
FILE *out;
/* Ignore link following (CWE-59) for brevity */

out = fopen(OUTFILE, "w");
if (out) {

fprintf(out, "hello world!\n");
fclose(out);

}

After running this program on a UNIX system, running the "ls -l" command might return the following output:

(result)

-rw-rw-rw- 1 username 13 Nov 24 17:58 hello.out

The "rw-rw-rw-" string indicates that the owner, group, and world (all users) can read the file and write to it.

Example 2

This code creates a home directory for a new user, and makes that user the owner of the directory. If the new directory cannot be owned by the user, the directory is deleted.

(bad code)

Example Language: PHP

function createUserDir($username){

$path = '/home/'.$username;
if(!mkdir($path)){

return false;

}
if(!chown($path,$username)){

rmdir($path);
return false;

}
return true;

}

Because the optional "mode" argument is omitted from the call to mkdir(), the directory is created with the default permissions 0777. Simply setting the new user as the owner of the directory does not explicitly change the permissions of the directory, leaving it with the default. This default allows any user to read and write to the directory, allowing an attack on the user's files. The code also fails to change the owner group of the directory, which may result in access by unexpected groups.

This code may also be vulnerable to Path Traversal (CWE-22) attacks if an attacker supplies a non alphanumeric username.

Example 3

The following code snippet might be used as a monitor to periodically record whether a web site is alive. To ensure that the file can always be modified, the code uses chmod() to make the file world-writable.

(bad code)

Example Language: Perl

$fileName = "secretFile.out";

if (-e $fileName) {

chmod 0777, $fileName;

}

my $outFH;
if (! open($outFH, ">>$fileName")) {

ExitError("Couldn't append to $fileName: $!");

}
my $dateString = FormatCurrentTime();
my $status = IsHostAlive("cwe.mitre.org");
print $outFH "$dateString cwe status: $status!\n";
close($outFH);

The first time the program runs, it might create a new file that inherits the permissions from its environment. A file listing might look like:

(result)

-rw-r--r-- 1 username 13 Nov 24 17:58 secretFile.out

This listing might occur when the user has a default umask of 022, which is a common setting. Depending on the nature of the file, the user might not have intended to make it readable by everyone on the system.

The next time the program runs, however - and all subsequent executions - the chmod will set the file's permissions so that the owner, group, and world (all users) can read the file and write to it:

(result)

-rw-rw-rw- 1 username 13 Nov 24 17:58 secretFile.out

Perhaps the programmer tried to do this because a different process uses different permissions that might prevent the file from being updated.

Example 4

This program creates and reads from an admin file to determine privilege information.

If the admin file doesn't exist, the program will create one. In order to create the file, the program must have write privileges to write to the file. After the file is created, the permissions need to be changed to read only.

(bad code)

Example Language: Go

const adminFile = "/etc/admin-users"
func createAdminFileIfNotExists() error {

file, err := os.Create(adminFile)
if err != nil {

return err

}
return nil

}

func changeModeOfAdminFile() error {

fileMode := os.FileMode(0440)
if err := os.Chmod(adminFile, fileMode); err != nil {

return err

}
return nil

}

os.Create will create a file with 0666 permissions before umask if the specified file does not exist. A typical umask of 0022 would result in the file having 0644 permissions. That is, the file would have world-writable and world-readable permissions.

In this scenario, it is advised to use the more customizable method of os.OpenFile with the os.O_WRONLY and os.O_CREATE flags specifying 0640 permissions to create the admin file.

This is because on a typical system where the umask is 0022, the perm 0640 applied in os.OpenFile will result in a file of 0620 where only the owner and group can write.

Example 5

The following command recursively sets world-readable permissions for a directory and all of its children:

(bad code)

Example Language: Shell

chmod -R ugo+r DIRNAME

If this command is run from a program, the person calling the program might not expect that all the files under the directory will be world-readable. If the directory is expected to contain private data, this could become a security problem.

Example 6

The following Azure command updates the settings for a storage account:

(bad code)

Example Language: Shell

az storage account update --name <storage-account> --resource-group <resource-group> --allow-blob-public-access true

However, "Allow Blob Public Access" is set to true, meaning that anonymous/public users can access blobs.

The command could be modified to disable "Allow Blob Public Access" by setting it to false.

(good code)

Example Language: Shell

az storage account update --name <storage-account> --resource-group <resource-group> --allow-blob-public-access false

Example 7

The following Google Cloud Storage command gets the settings for a storage account named 'BUCKET_NAME':

(informative)

Example Language: Shell

gsutil iam get gs://BUCKET_NAME

Suppose the command returns the following result:

(bad code)

Example Language: JSON

{

"bindings":[{

"members":[

"projectEditor: PROJECT-ID",
"projectOwner: PROJECT-ID"

],
"role":"roles/storage.legacyBucketOwner"

},
{

"members":[

"allUsers",
"projectViewer: PROJECT-ID"
],
"role":"roles/storage.legacyBucketReader"

}

]

}

This result includes the "allUsers" or IAM role added as members, causing this policy configuration to allow public access to cloud storage resources. There would be a similar concern if "allAuthenticatedUsers" was present.

The command could be modified to remove "allUsers" and/or "allAuthenticatedUsers" as follows:

(good code)

Example Language: Shell

gsutil iam ch -d allUsers gs://BUCKET_NAME
gsutil iam ch -d allAuthenticatedUsers gs://BUCKET_NAME

Selected Observed Examples

Reference	Description
CVE-2022-29527	Go application for cloud management creates a world-writable sudoers file that allows local attackers to inject sudo rules and escalate privileges to root by winning a race condition.
CVE-2009-3482	Anti-virus product sets insecure "Everyone: Full Control" permissions for files under the "Program Files" folder, allowing attackers to replace executables with Trojan horses.
CVE-2009-3897	Product creates directories with 0777 permissions at installation, allowing users to gain privileges and access a socket used for authentication.
CVE-2009-3489	Photo editor installs a service with an insecure security descriptor, allowing users to stop or start the service, or execute commands as SYSTEM.
CVE-2020-15708	socket created with insecure permissions
CVE-2009-3289	Library function copies a file to a new target and uses the source file's permissions for the target, which is incorrect when the source file is a symbolic link, which typically has 0777 permissions.
CVE-2009-0115	Device driver uses world-writable permissions for a socket file, allowing attackers to inject arbitrary commands.
CVE-2009-1073	LDAP server stores a cleartext password in a world-readable file.
CVE-2009-0141	Terminal emulator creates TTY devices with world-writable permissions, allowing an attacker to write to the terminals of other users.
CVE-2008-0662	VPN product stores user credentials in a registry key with "Everyone: Full Control" permissions, allowing attackers to steal the credentials.
CVE-2008-0322	Driver installs its device interface with "Everyone: Write" permissions.
CVE-2009-3939	Driver installs a file with world-writable permissions.
CVE-2009-3611	Product changes permissions to 0777 before deleting a backup; the permissions stay insecure for subsequent backups.
CVE-2007-6033	Product creates a share with "Everyone: Full Control" permissions, allowing arbitrary program execution.
CVE-2007-5544	Product uses "Everyone: Full Control" permissions for memory-mapped files (shared memory) in inter-process communication, allowing attackers to tamper with a session.
CVE-2005-4868	Database product uses read/write permissions for everyone for its shared memory, allowing theft of credentials.
CVE-2004-1714	Security product uses "Everyone: Full Control" permissions for its configuration files.
CVE-2001-0006	"Everyone: Full Control" permissions assigned to a mutex allows users to disable network connectivity.
CVE-2002-0969	Chain: database product contains buffer overflow that is only reachable through a .ini configuration file - which has "Everyone: Full Control" permissions.

Detection Methods

Method	Details
Automated Static Analysis	Automated static analysis may be effective in detecting permission problems for system resources such as files, directories, shared memory, device interfaces, etc. Automated techniques may be able to detect the use of library functions that modify permissions, then analyze function calls for arguments that contain potentially insecure values. However, since the software's intended security policy might allow loose permissions for certain operations (such as publishing a file on a web server), automated static analysis may produce some false positives - i.e., warnings that do not have any security consequences or require any code changes. When custom permissions models are used - such as defining who can read messages in a particular forum in a bulletin board system - these can be difficult to detect using automated static analysis. It may be possible to define custom signatures that identify any custom functions that implement the permission checks and assignments.
Automated Dynamic Analysis	Automated dynamic analysis may be effective in detecting permission problems for system resources such as files, directories, shared memory, device interfaces, etc. However, since the software's intended security policy might allow loose permissions for certain operations (such as publishing a file on a web server), automated dynamic analysis may produce some false positives - i.e., warnings that do not have any security consequences or require any code changes. When custom permissions models are used - such as defining who can read messages in a particular forum in a bulletin board system - these can be difficult to detect using automated dynamic analysis. It may be possible to define custom signatures that identify any custom functions that implement the permission checks and assignments.
Manual Analysis	This weakness can be detected using tools and techniques that require manual (human) analysis, such as penetration testing, threat modeling, and interactive tools that allow the tester to record and modify an active session. Note:These may be more effective than strictly automated techniques. This is especially the case with weaknesses that are related to design and business rules.
Manual Static Analysis	Manual static analysis may be effective in detecting the use of custom permissions models and functions. The code could then be examined to identifying usage of the related functions. Then the human analyst could evaluate permission assignments in the context of the intended security model of the software.
Manual Dynamic Analysis	Manual dynamic analysis may be effective in detecting the use of custom permissions models and functions. The program could then be executed with a focus on exercising code paths that are related to the custom permissions. Then the human analyst could evaluate permission assignments in the context of the intended security model of the software.
Fuzzing	Fuzzing is not effective in detecting this weakness.
Black Box	Use monitoring tools that examine the software's process as it interacts with the operating system and the network. This technique is useful in cases when source code is unavailable, if the software was not developed by you, or if you want to verify that the build phase did not introduce any new weaknesses. Examples include debuggers that directly attach to the running process; system-call tracing utilities such as truss (Solaris) and strace (Linux); system activity monitors such as FileMon, RegMon, Process Monitor, and other Sysinternals utilities (Windows); and sniffers and protocol analyzers that monitor network traffic. Attach the monitor to the process and watch for library functions or system calls on OS resources such as files, directories, and shared memory. Examine the arguments to these calls to infer which permissions are being used. Note:Note that this technique is only useful for permissions issues related to system resources. It is not likely to detect application-level business rules that are related to permissions, such as if a user of a blog system marks a post as "private," but the blog system inadvertently marks it as "public."
Automated Static Analysis - Binary or Bytecode	According to SOAR, the following detection techniques may be useful: Cost effective for partial coverage: Inter-application Flow Analysis Effectiveness: SOAR Partial
Manual Static Analysis - Binary or Bytecode	According to SOAR, the following detection techniques may be useful: Cost effective for partial coverage: Binary / Bytecode disassembler - then use manual analysis for vulnerabilities & anomalies Effectiveness: SOAR Partial
Dynamic Analysis with Automated Results Interpretation	According to SOAR, the following detection techniques may be useful: Cost effective for partial coverage: Host-based Vulnerability Scanners - Examine configuration for flaws, verifying that audit mechanisms work, ensure host configuration meets certain predefined criteria Web Application Scanner Web Services Scanner Database Scanners Effectiveness: SOAR Partial
Dynamic Analysis with Manual Results Interpretation	According to SOAR, the following detection techniques may be useful: Highly cost effective: Host Application Interface Scanner Cost effective for partial coverage: Fuzz Tester Framework-based Fuzzer Automated Monitored Execution Forced Path Execution Effectiveness: High
Manual Static Analysis - Source Code	According to SOAR, the following detection techniques may be useful: Highly cost effective: Manual Source Code Review (not inspections) Cost effective for partial coverage: Focused Manual Spotcheck - Focused manual analysis of source Effectiveness: High
Automated Static Analysis - Source Code	According to SOAR, the following detection techniques may be useful: Cost effective for partial coverage: Context-configured Source Code Weakness Analyzer Effectiveness: SOAR Partial
Automated Static Analysis	According to SOAR, the following detection techniques may be useful: Cost effective for partial coverage: Configuration Checker Effectiveness: SOAR Partial
Architecture or Design Review	According to SOAR, the following detection techniques may be useful: Highly cost effective: Formal Methods / Correct-By-Construction Cost effective for partial coverage: Inspection (IEEE 1028 standard) (can apply to requirements, design, source code, etc.) Effectiveness: High

Memberships

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	743	CERT C Secure Coding Standard (2008) Chapter 10 - Input Output (FIO)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	753	2009 Top 25 - Porous Defenses
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	803	2010 Top 25 - Porous Defenses
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	815	OWASP Top Ten 2010 Category A6 - Security Misconfiguration
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	857	The CERT Oracle Secure Coding Standard for Java (2011) Chapter 14 - Input Output (FIO)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	859	The CERT Oracle Secure Coding Standard for Java (2011) Chapter 16 - Platform Security (SEC)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	860	The CERT Oracle Secure Coding Standard for Java (2011) Chapter 17 - Runtime Environment (ENV)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	866	2011 Top 25 - Porous Defenses
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	877	CERT C++ Secure Coding Section 09 - Input Output (FIO)
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	884	CWE Cross-section
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	946	SFP Secondary Cluster: Insecure Resource Permissions
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1147	SEI CERT Oracle Secure Coding Standard for Java - Guidelines 13. Input Output (FIO)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1149	SEI CERT Oracle Secure Coding Standard for Java - Guidelines 15. Platform Security (SEC)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1150	SEI CERT Oracle Secure Coding Standard for Java - Guidelines 16. Runtime Environment (ENV)
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1200	Weaknesses in the 2019 CWE Top 25 Most Dangerous Software Errors
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1308	CISQ Quality Measures - Security
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1337	Weaknesses in the 2021 CWE Top 25 Most Dangerous Software Weaknesses
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1340	CISQ Data Protection Measures
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1350	Weaknesses in the 2020 CWE Top 25 Most Dangerous Software Weaknesses
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1396	Comprehensive Categorization: Access Control

Vulnerability Mapping Notes

Usage	ALLOWED-WITH-REVIEW (this CWE ID could be used to map to real-world vulnerabilities in limited situations requiring careful review)
Reason	Frequent Misuse
Rationale	While the name itself indicates an assignment of permissions for resources, this is often misused for vulnerabilities in which "permissions" are not checked, which is an "authorization" weakness (CWE-285 or descendants) within CWE's model [REF-1287].
Comments	Closely analyze the specific mistake that is allowing the resource to be exposed, and perform a CWE mapping for that mistake.

Notes

Maintenance

The relationships between privileges, permissions, and actors (e.g. users and groups) need further refinement within the Research view. One complication is that these concepts apply to two different pillars, related to control of resources (CWE-664) and protection mechanism failures (CWE-693).

Taxonomy Mappings

Mapped Taxonomy Name	Node ID	Mapped Node Name
The CERT Oracle Secure Coding Standard for Java (2011)	FIO03-J	Create files with appropriate access permission
The CERT Oracle Secure Coding Standard for Java (2011)	SEC01-J	Do not allow tainted variables in privileged blocks
The CERT Oracle Secure Coding Standard for Java (2011)	ENV03-J	Do not grant dangerous combinations of permissions
CERT C Secure Coding	FIO06-C	Create files with appropriate access permissions

Related Attack Patterns

CAPEC-ID	Attack Pattern Name
CAPEC-1	Accessing Functionality Not Properly Constrained by ACLs
CAPEC-122	Privilege Abuse
CAPEC-127	Directory Indexing
CAPEC-17	Using Malicious Files
CAPEC-180	Exploiting Incorrectly Configured Access Control Security Levels
CAPEC-206	Signing Malicious Code
CAPEC-234	Hijacking a privileged process
CAPEC-60	Reusing Session IDs (aka Session Replay)
CAPEC-61	Session Fixation
CAPEC-62	Cross Site Request Forgery
CAPEC-642	Replace Binaries

References

[REF-62]	Mark Dowd, John McDonald and Justin Schuh. "The Art of Software Security Assessment". Chapter 9, "File Permissions." Page 495. 1st Edition. Addison Wesley. 2006.
[REF-207]	John Viega and Gary McGraw. "Building Secure Software: How to Avoid Security Problems the Right Way". Chapter 8, "Access Control." Page 194. 1st Edition. Addison-Wesley. 2002.
[REF-594]	Jason Lam. "Top 25 Series - Rank 21 - Incorrect Permission Assignment for Critical Response". SANS Software Security Institute. 2010-03-24. <http://software-security.sans.org/blog/2010/03/24/top-25-series-rank-21-incorrect-permission-assignment-for-critical-response>.
[REF-199]	NIST. "United States Government Configuration Baseline (USGCB)". <https://csrc.nist.gov/Projects/United-States-Government-Configuration-Baseline>. (URL validated: 2023-03-28)
[REF-1287]	MITRE. "Supplemental Details - 2022 CWE Top 25". Details of Problematic Mappings. 2022-06-28. <https://cwe.mitre.org/top25/archive/2022/2022_cwe_top25_supplemental.html#problematicMappingDetails>. (URL validated: 2024-11-17)
[REF-1307]	Center for Internet Security. "CIS Microsoft Azure Foundations Benchmark version 1.5.0". Section 3.7. 2022-08-16. <https://www.cisecurity.org/benchmark/azure>. (URL validated: 2023-01-19)
[REF-1327]	Center for Internet Security. "CIS Google Cloud Computing Platform Benchmark version 1.3.0". Section 5.1. 2022-03-31. <https://www.cisecurity.org/benchmark/google_cloud_computing_platform>. (URL validated: 2023-04-24)

Content History

Submissions
Submission Date	Submitter	Organization
2008-09-08 (CWE 1.0, 2008-09-09)	CWE Content Team	MITRE
2008-09-08 (CWE 1.0, 2008-09-09)	new weakness-focused entry for Research view.
Modifications
Modification Date	Modifier	Organization
2023-06-29	CWE Content Team	MITRE
2023-06-29	updated Mapping_Notes, Relationships
2023-04-27	CWE Content Team	MITRE
2023-04-27	updated Demonstrative_Examples, Description, Potential_Mitigations, References, Relationships
2023-01-31	CWE Content Team	MITRE
2023-01-31	updated Applicable_Platforms, Description, References
2022-10-13	CWE Content Team	MITRE
2022-10-13	updated Demonstrative_Examples, Observed_Examples, References
2021-07-20	CWE Content Team	MITRE
2021-07-20	updated Observed_Examples, Relationships
2020-12-10	CWE Content Team	MITRE
2020-12-10	updated Relationships
2020-08-20	CWE Content Team	MITRE
2020-08-20	updated Relationships
2020-02-24	CWE Content Team	MITRE
2020-02-24	updated Applicable_Platforms, Description, Detection_Factors, Modes_of_Introduction, Relationships
2019-09-19	CWE Content Team	MITRE
2019-09-19	updated Maintenance_Notes, Relationships
2019-06-20	CWE Content Team	MITRE
2019-06-20	updated Relationships
2019-01-03	CWE Content Team	MITRE
2019-01-03	updated Related_Attack_Patterns, Relationships, Taxonomy_Mappings
2017-11-08	CWE Content Team	MITRE
2017-11-08	updated Likelihood_of_Exploit, Modes_of_Introduction, References, Relationships, Taxonomy_Mappings
2017-01-19	CWE Content Team	MITRE
2017-01-19	updated Related_Attack_Patterns, Relationships
2014-07-30	CWE Content Team	MITRE
2014-07-30	updated Detection_Factors, Relationships
2013-07-17	CWE Content Team	MITRE
2013-07-17	updated References
2012-10-30	CWE Content Team	MITRE
2012-10-30	updated Potential_Mitigations
2012-05-11	CWE Content Team	MITRE
2012-05-11	updated References, Related_Attack_Patterns, Relationships, Taxonomy_Mappings
2011-09-13	CWE Content Team	MITRE
2011-09-13	updated Potential_Mitigations, References, Relationships, Taxonomy_Mappings
2011-06-27	CWE Content Team	MITRE
2011-06-27	updated Relationships
2011-06-01	CWE Content Team	MITRE
2011-06-01	updated Common_Consequences, Relationships, Taxonomy_Mappings
2011-03-29	CWE Content Team	MITRE
2011-03-29	updated Demonstrative_Examples, Description, Relationships
2010-12-13	CWE Content Team	MITRE
2010-12-13	updated Potential_Mitigations
2010-09-27	CWE Content Team	MITRE
2010-09-27	updated Potential_Mitigations, Relationships
2010-06-21	CWE Content Team	MITRE
2010-06-21	updated Common_Consequences, Detection_Factors, Potential_Mitigations, References, Relationships
2010-04-05	CWE Content Team	MITRE
2010-04-05	updated Potential_Mitigations, Related_Attack_Patterns
2010-02-16	CWE Content Team	MITRE
2010-02-16	updated Relationships
2009-12-28	CWE Content Team	MITRE
2009-12-28	updated Applicable_Platforms, Common_Consequences, Demonstrative_Examples, Detection_Factors, Modes_of_Introduction, Observed_Examples, Potential_Mitigations, References
2009-05-27	CWE Content Team	MITRE
2009-05-27	updated Name
2009-03-10	CWE Content Team	MITRE
2009-03-10	updated Potential_Mitigations, Related_Attack_Patterns
2009-01-12	CWE Content Team	MITRE
2009-01-12	updated Description, Likelihood_of_Exploit, Name, Potential_Mitigations, Relationships
Previous Entry Names
Change Date	Previous Entry Name
2009-01-12	Insecure Permission Assignment for Resource
2009-05-27	Insecure Permission Assignment for Critical Resource

Weakness ID: 190

View customized information:

Description

Alternate Terms

Overflow	The terms "overflow" and "wraparound" are used interchangeably by some people, but they can have more precise distinctions by others. See Terminology Notes.
Wraparound	The terms "overflow" and "wraparound" are used interchangeably by some people, but they can have more precise distinctions by others. See Terminology Notes.
wrap, wrap-around, wrap around	Alternate spellings of "wraparound"

Common Consequences

Impact	Details
DoS: Crash, Exit, or Restart; DoS: Resource Consumption (Memory); DoS: Instability	Scope: Availability This weakness can generally lead to undefined behavior and therefore crashes. When the calculated result is used for resource allocation, this weakness can cause too many (or too few) resources to be allocated, possibly enabling crashes if the product requests more resources than can be provided.
Modify Memory	Scope: Integrity If the value in question is important to data (as opposed to flow), simple data corruption has occurred. Also, if the overflow/wraparound results in other conditions such as buffer overflows, further memory corruption may occur.
Execute Unauthorized Code or Commands; Bypass Protection Mechanism	Scope: Confidentiality, Availability, Access Control This weakness can sometimes trigger buffer overflows, which can be used to execute arbitrary code. This is usually outside the scope of the product's implicit security policy.
Alter Execution Logic; DoS: Crash, Exit, or Restart; DoS: Resource Consumption (CPU)	Scope: Availability, Other If the overflow/wraparound occurs in a loop index variable, this could cause the loop to terminate at the wrong time - too early, too late, or not at all (i.e., infinite loops). With too many iterations, some loops could consume too many resources such as memory, file handles, etc., possibly leading to a crash or other DoS.
Bypass Protection Mechanism	Scope: Access Control If integer values are used in security-critical decisions, such as calculating quotas or allocation limits, integer overflows can be used to cause an incorrect security decision.

Potential Mitigations

Phase(s)	Mitigation
Requirements	Ensure that all protocols are strictly defined, such that all out-of-bounds behavior can be identified simply, and require strict conformance to the protocol.
Requirements	Strategy: Language Selection Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. If possible, choose a language or compiler that performs automatic bounds checking.
Architecture and Design	Strategy: Libraries or Frameworks Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. Use libraries or frameworks that make it easier to handle numbers without unexpected consequences. Examples include safe integer handling packages such as SafeInt (C++) or IntegerLib (C or C++). [REF-106]
Implementation	Strategy: Input Validation Perform input validation on any numeric input by ensuring that it is within the expected range. Enforce that the input meets both the minimum and maximum requirements for the expected range. Use unsigned integers where possible. This makes it easier to perform validation for integer overflows. When signed integers are required, ensure that the range check includes minimum values as well as maximum values.
Implementation	Understand the programming language's underlying representation and how it interacts with numeric calculation (CWE-681). Pay close attention to byte size discrepancies, precision, signed/unsigned distinctions, truncation, conversion and casting between types, "not-a-number" calculations, and how the language handles numbers that are too large or too small for its underlying representation. [REF-7] Also be careful to account for 32-bit, 64-bit, and other potential differences that may affect the numeric representation.
Architecture and Design	For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.
Implementation	Strategy: Compilation or Build Hardening Examine compiler warnings closely and eliminate problems with potential security implications, such as signed / unsigned mismatch in memory operations, or use of uninitialized variables. Even if the weakness is rarely exploitable, a single failure may lead to the compromise of the entire system.

Relationships

Relevant to the view "Research Concepts" (View-1000)

Nature	Type	ID	Name
ChildOf	Pillar - a weakness that is the most abstract type of weakness and represents a theme for all class/base/variant weaknesses related to it. A Pillar is different from a Category as a Pillar is still technically a type of weakness that describes a mistake, while a Category represents a common characteristic used to group related things.	682	Incorrect Calculation
ParentOf	Chain - a Compound Element that is a sequence of two or more separate weaknesses that can be closely linked together within software. One weakness, X, can directly create the conditions that are necessary to cause another weakness, Y, to enter a vulnerable condition. When this happens, CWE refers to X as "primary" to Y, and Y is "resultant" from X. Chains can involve more than two weaknesses, and in some cases, they might have a tree-like structure.	680	Integer Overflow to Buffer Overflow
PeerOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	128	Wrap-around Error
PeerOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	1339	Insufficient Precision or Accuracy of a Real Number
CanPrecede	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	119	Improper Restriction of Operations within the Bounds of a Memory Buffer

Relevant to the view "Software Development" (View-699)

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	189	Numeric Errors

Relevant to the view "Weaknesses for Simplified Mapping of Published Vulnerabilities" (View-1003)

Nature	Type	ID	Name
ChildOf	Pillar - a weakness that is the most abstract type of weakness and represents a theme for all class/base/variant weaknesses related to it. A Pillar is different from a Category as a Pillar is still technically a type of weakness that describes a mistake, while a Category represents a common characteristic used to group related things.	682	Incorrect Calculation

Relevant to the view "Seven Pernicious Kingdoms" (View-700)

Nature	Type	ID	Name
ChildOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	20	Improper Input Validation

Modes Of Introduction

Phase	Note
Implementation	This weakness may become security critical when determining the offset or size in behaviors such as memory allocation, copying, and concatenation.

Applicable Platforms

Languages

C (Often Prevalent)

Class: Not Language-Specific (Undetermined Prevalence)

Likelihood Of Exploit

Medium

Demonstrative Examples

Example 1

The following image processing code allocates a table for images.

(bad code)

Example Language: C

img_t table_ptr; /*struct containing img data, 10kB each*/
int num_imgs;
...
num_imgs = get_num_imgs();
table_ptr = (img_t*)malloc(sizeof(img_t)*num_imgs);
...

Example 2

The following code excerpt from OpenSSH 3.3 demonstrates a classic case of integer overflow:

(bad code)

Example Language: C

nresp = packet_get_int();
if (nresp > 0) {

response = xmalloc(nresp*sizeof(char*));
for (i = 0; i < nresp; i++) response[i] = packet_get_string(NULL);

}

If nresp has the value 1073741824 and sizeof(char*) has its typical value of 4, then the result of the operation nresp*sizeof(char*) overflows, and the argument to xmalloc() will be 0. Most malloc() implementations will happily allocate a 0-byte buffer, causing the subsequent loop iterations to overflow the heap buffer response.

Example 3

Integer overflows can be complicated and difficult to detect. The following example is an attempt to show how an integer overflow may lead to undefined looping behavior:

(bad code)

Example Language: C

short int bytesRec = 0;
char buf[SOMEBIGNUM];

while(bytesRec < MAXGET) {

bytesRec += getFromInput(buf+bytesRec);

}

In the above case, it is entirely possible that bytesRec may overflow, continuously creating a lower number than MAXGET and also overwriting the first MAXGET-1 bytes of buf.

Example 4

In this example the method determineFirstQuarterRevenue is used to determine the first quarter revenue for an accounting/business application. The method retrieves the monthly sales totals for the first three months of the year, calculates the first quarter sales totals from the monthly sales totals, calculates the first quarter revenue based on the first quarter sales, and finally saves the first quarter revenue results to the database.

(bad code)

Example Language: C

#define JAN 1
#define FEB 2
#define MAR 3

short getMonthlySales(int month) {...}

float calculateRevenueForQuarter(short quarterSold) {...}

int determineFirstQuarterRevenue() {

// Variable for sales revenue for the quarter
float quarterRevenue = 0.0f;

short JanSold = getMonthlySales(JAN); /* Get sales in January */
short FebSold = getMonthlySales(FEB); /* Get sales in February */
short MarSold = getMonthlySales(MAR); /* Get sales in March */

// Calculate quarterly total
short quarterSold = JanSold + FebSold + MarSold;

// Calculate the total revenue for the quarter
quarterRevenue = calculateRevenueForQuarter(quarterSold);

saveFirstQuarterRevenue(quarterRevenue);

return 0;

}

However, in this example the primitive type short int is used for both the monthly and the quarterly sales variables. In C the short int primitive type has a maximum value of 32768. This creates a potential integer overflow if the value for the three monthly sales adds up to more than the maximum value for the short int primitive type. An integer overflow can lead to data corruption, unexpected behavior, infinite loops and system crashes. To correct the situation the appropriate primitive type should be used, as in the example below, and/or provide some validation mechanism to ensure that the maximum value for the primitive type is not exceeded.

(good code)

Example Language: C

...
float calculateRevenueForQuarter(long quarterSold) {...}

int determineFirstQuarterRevenue() {

...
// Calculate quarterly total
long quarterSold = JanSold + FebSold + MarSold;

// Calculate the total revenue for the quarter
quarterRevenue = calculateRevenueForQuarter(quarterSold);

...

}

Note that an integer overflow could also occur if the quarterSold variable has a primitive type long but the method calculateRevenueForQuarter has a parameter of type short.

Selected Observed Examples

Reference	Description
CVE-2025-27363	Font rendering library does not properly handle assigning a signed short value to an unsigned long (CWE-195), leading to an integer wraparound (CWE-190), causing too small of a buffer (CWE-131), leading to an out-of-bounds write (CWE-787).
CVE-2021-43537	Chain: in a web browser, an unsigned 64-bit integer is forcibly cast to a 32-bit integer (CWE-681) and potentially leading to an integer overflow (CWE-190). If an integer overflow occurs, this can cause heap memory corruption (CWE-122)
CVE-2022-21668	Chain: Python library does not limit the resources used to process images that specify a very large number of bands (CWE-1284), leading to excessive memory consumption (CWE-789) or an integer overflow (CWE-190).
CVE-2022-0545	Chain: 3D renderer has an integer overflow (CWE-190) leading to write-what-where condition (CWE-123) using a crafted image.
CVE-2021-30860	Chain: improper input validation (CWE-20) leads to integer overflow (CWE-190) in mobile OS, as exploited in the wild per CISA KEV.
CVE-2021-30663	Chain: improper input validation (CWE-20) leads to integer overflow (CWE-190) in mobile OS, as exploited in the wild per CISA KEV.
CVE-2018-10887	Chain: unexpected sign extension (CWE-194) leads to integer overflow (CWE-190), causing an out-of-bounds read (CWE-125)
CVE-2019-1010006	Chain: compiler optimization (CWE-733) removes or modifies code used to detect integer overflow (CWE-190), allowing out-of-bounds write (CWE-787).
CVE-2010-1866	Chain: integer overflow (CWE-190) causes a negative signed value, which later bypasses a maximum-only check (CWE-839), leading to heap-based buffer overflow (CWE-122).
CVE-2010-2753	Chain: integer overflow leads to use-after-free
CVE-2005-1513	Chain: integer overflow in securely-coded mail program leads to buffer overflow. In 2005, this was regarded as unrealistic to exploit, but in 2020, it was rediscovered to be easier to exploit due to evolutions of the technology.
CVE-2002-0391	Integer overflow via a large number of arguments.
CVE-2002-0639	Integer overflow in OpenSSH as listed in the demonstrative examples.
CVE-2005-1141	Image with large width and height leads to integer overflow.
CVE-2005-0102	Length value of -1 leads to allocation of 0 bytes and resultant heap overflow.
CVE-2004-2013	Length value of -1 leads to allocation of 0 bytes and resultant heap overflow.
CVE-2017-1000121	chain: unchecked message size metadata allows integer overflow (CWE-190) leading to buffer overflow (CWE-119).
CVE-2013-1591	Chain: an integer overflow (CWE-190) in the image size calculation causes an infinite loop (CWE-835) which sequentially allocates buffers without limits (CWE-1325) until the stack is full.

Detection Methods

Method	Details
Automated Static Analysis	This weakness can often be detected using automated static analysis tools. Many modern tools use data flow analysis or constraint-based techniques to minimize the number of false positives. Effectiveness: High
Black Box	Sometimes, evidence of this weakness can be detected using dynamic tools and techniques that interact with the product using large test suites with many diverse inputs, such as fuzz testing (fuzzing), robustness testing, and fault injection. The product's operation may slow down, but it should not become unstable, crash, or generate incorrect results. Effectiveness: Moderate Note:Without visibility into the code, black box methods may not be able to sufficiently distinguish this weakness from others, requiring follow-up manual methods to diagnose the underlying problem.
Manual Analysis	This weakness can be detected using tools and techniques that require manual (human) analysis, such as penetration testing, threat modeling, and interactive tools that allow the tester to record and modify an active session. Specifically, manual static analysis is useful for evaluating the correctness of allocation calculations. This can be useful for detecting overflow conditions (CWE-190) or similar weaknesses that might have serious security impacts on the program. Effectiveness: High Note:These may be more effective than strictly automated techniques. This is especially the case with weaknesses that are related to design and business rules.
Automated Static Analysis - Binary or Bytecode	According to SOAR, the following detection techniques may be useful: Highly cost effective: Bytecode Weakness Analysis - including disassembler + source code weakness analysis Binary Weakness Analysis - including disassembler + source code weakness analysis Effectiveness: High
Dynamic Analysis with Manual Results Interpretation	According to SOAR, the following detection techniques may be useful: Cost effective for partial coverage: Fuzz Tester Framework-based Fuzzer Effectiveness: SOAR Partial
Manual Static Analysis - Source Code	According to SOAR, the following detection techniques may be useful: Cost effective for partial coverage: Manual Source Code Review (not inspections) Effectiveness: SOAR Partial
Automated Static Analysis - Source Code	According to SOAR, the following detection techniques may be useful: Highly cost effective: Source code Weakness Analyzer Context-configured Source Code Weakness Analyzer Effectiveness: High
Architecture or Design Review	According to SOAR, the following detection techniques may be useful: Highly cost effective: Formal Methods / Correct-By-Construction Cost effective for partial coverage: Inspection (IEEE 1028 standard) (can apply to requirements, design, source code, etc.) Effectiveness: High

Functional Areas

Number Processing
Memory Management
Counters

Memberships

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	738	CERT C Secure Coding Standard (2008) Chapter 5 - Integers (INT)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	742	CERT C Secure Coding Standard (2008) Chapter 9 - Memory Management (MEM)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	802	2010 Top 25 - Risky Resource Management
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	865	2011 Top 25 - Risky Resource Management
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	872	CERT C++ Secure Coding Section 04 - Integers (INT)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	876	CERT C++ Secure Coding Section 08 - Memory Management (MEM)
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	884	CWE Cross-section
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	998	SFP Secondary Cluster: Glitch in Computation
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1137	SEI CERT Oracle Secure Coding Standard for Java - Guidelines 03. Numeric Types and Operations (NUM)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1158	SEI CERT C Coding Standard - Guidelines 04. Integers (INT)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1162	SEI CERT C Coding Standard - Guidelines 08. Memory Management (MEM)
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1200	Weaknesses in the 2019 CWE Top 25 Most Dangerous Software Errors
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1337	Weaknesses in the 2021 CWE Top 25 Most Dangerous Software Weaknesses
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1350	Weaknesses in the 2020 CWE Top 25 Most Dangerous Software Weaknesses
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1387	Weaknesses in the 2022 CWE Top 25 Most Dangerous Software Weaknesses
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1408	Comprehensive Categorization: Incorrect Calculation
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1425	Weaknesses in the 2023 CWE Top 25 Most Dangerous Software Weaknesses
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1430	Weaknesses in the 2024 CWE Top 25 Most Dangerous Software Weaknesses

Vulnerability Mapping Notes

Usage

ALLOWED

(this CWE ID may be used to map to real-world vulnerabilities)

Reason

Acceptable-Use

Rationale

This CWE entry is at the Base level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.

Comments

Be careful of terminology problems with "overflow," "underflow," and "wraparound" - see Terminology Notes. Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction.

Suggestions

CWE-ID	Comment
CWE-191	Integer Underflow (Wrap or Wraparound). Consider CWE-191 when the result is less than the minimum value that can be represented (sometimes called "underflows").

Notes

Relationship

Integer overflows can be primary to buffer overflows when they cause less memory to be allocated than expected.

Terminology

"Integer overflow" is sometimes used to cover several types of errors, including signedness errors, or buffer overflows that involve manipulation of integer data types instead of characters. Part of the confusion results from the fact that 0xffffffff is -1 in a signed context. Other confusion also arises because of the role that integer overflows have in chains.

A "wraparound" is a well-defined, standard behavior that follows specific rules for how to handle situations when the intended numeric value is too large or too small to be represented, as specified in standards such as C11.

"Overflow" is sometimes conflated with "wraparound" but typically indicates a non-standard or undefined behavior.

The "overflow" term is sometimes used to indicate cases where either the maximum or the minimum is exceeded, but others might only use "overflow" to indicate exceeding the maximum while using "underflow" for exceeding the minimum.

Some people use "overflow" to mean any value outside the representable range - whether greater than the maximum, or less than the minimum - but CWE uses "underflow" for cases in which the intended result is less than the minimum.

See [REF-1440] for additional explanation of the ambiguity of terminology.

Other

While there may be circumstances in which the logic intentionally relies on wrapping - such as with modular arithmetic in timers or counters - it can have security consequences if the wrap is unexpected. This is especially the case if the integer overflow can be triggered using user-supplied inputs.

Taxonomy Mappings

Mapped Taxonomy Name	Node ID	Fit	Mapped Node Name
PLOVER			Integer overflow (wrap or wraparound)
7 Pernicious Kingdoms			Integer Overflow
CLASP			Integer overflow
CERT C Secure Coding	INT18-C	CWE More Abstract	Evaluate integer expressions in a larger size before comparing or assigning to that size
CERT C Secure Coding	INT30-C	CWE More Abstract	Ensure that unsigned integer operations do not wrap
CERT C Secure Coding	INT32-C	Imprecise	Ensure that operations on signed integers do not result in overflow
CERT C Secure Coding	INT35-C		Evaluate integer expressions in a larger size before comparing or assigning to that size
CERT C Secure Coding	MEM07-C	CWE More Abstract	Ensure that the arguments to calloc(), when multiplied, do not wrap
CERT C Secure Coding	MEM35-C		Allocate sufficient memory for an object
WASC	3		Integer Overflows
Software Fault Patterns	SFP1		Glitch in computation
ISA/IEC 62443	Part 3-3		Req SR 3.5
ISA/IEC 62443	Part 3-3		Req SR 7.2
ISA/IEC 62443	Part 4-1		Req SR-2
ISA/IEC 62443	Part 4-1		Req SI-2
ISA/IEC 62443	Part 4-1		Req SVV-1
ISA/IEC 62443	Part 4-1		Req SVV-3
ISA/IEC 62443	Part 4-2		Req CR 3.5
ISA/IEC 62443	Part 4-2		Req CR 7.2

Related Attack Patterns

CAPEC-ID	Attack Pattern Name
CAPEC-92	Forced Integer Overflow

References

[REF-145]	Yves Younan. "An overview of common programming security vulnerabilities and possible solutions". Student thesis section 5.4.3. 2003-08. <http://fort-knox.org/thesis.pdf>.
[REF-146]	blexim. "Basic Integer Overflows". Phrack - Issue 60, Chapter 10. <http://www.phrack.org/issues.html?issue=60&id=10#article>.
[REF-7]	Michael Howard and David LeBlanc. "Writing Secure Code". Chapter 20, "Integer Overflows" Page 620. 2nd Edition. Microsoft Press. 2002-12-04. <https://www.microsoftpressstore.com/store/writing-secure-code-9780735617223>.
[REF-44]	Michael Howard, David LeBlanc and John Viega. "24 Deadly Sins of Software Security". "Sin 7: Integer Overflows." Page 119. McGraw-Hill. 2010.
[REF-106]	David LeBlanc and Niels Dekker. "SafeInt". <http://safeint.codeplex.com/>.
[REF-150]	Johannes Ullrich. "Top 25 Series - Rank 17 - Integer Overflow Or Wraparound". SANS Software Security Institute. 2010-03-18. <http://software-security.sans.org/blog/2010/03/18/top-25-series-rank-17-integer-overflow-or-wraparound>.
[REF-62]	Mark Dowd, John McDonald and Justin Schuh. "The Art of Software Security Assessment". Chapter 6, "Signed Integer Boundaries", Page 220. 1st Edition. Addison Wesley. 2006.
[REF-1440]	"Integer overflow". Definition variations and ambiguity. Wikipedia. 2024-06-11. <https://en.wikipedia.org/wiki/Integer_overflow>. (URL validated: 2024-06-30)

Content History

Submissions
Submission Date	Submitter	Organization
2006-07-19 (CWE Draft 3, 2006-07-19)	PLOVER
2006-07-19 (CWE Draft 3, 2006-07-19)
Contributions
Contribution Date	Contributor	Organization
2023-04-25	"Mapping CWE to 62443" Sub-Working Group	CWE-CAPEC ICS/OT SIG
2023-04-25	Suggested mappings to ISA/IEC 62443.
2024-02-29 (CWE 4.15, 2024-07-16)	Abhi Balakrishnan
2024-02-29 (CWE 4.15, 2024-07-16)	Provided diagram to improve CWE usability
Modifications
Modification Date	Modifier	Organization
2025-04-03 (CWE 4.17, 2025-04-03)	CWE Content Team	MITRE
2025-04-03 (CWE 4.17, 2025-04-03)	updated Applicable_Platforms, Observed_Examples
2024-11-19 (CWE 4.16, 2024-11-19)	CWE Content Team	MITRE
2024-11-19 (CWE 4.16, 2024-11-19)	updated Relationships
2024-07-16 (CWE 4.15, 2024-07-16)	CWE Content Team	MITRE
2024-07-16 (CWE 4.15, 2024-07-16)	updated Alternate_Terms, Common_Consequences, Description, Diagram, Mapping_Notes, Modes_of_Introduction, Other_Notes, References, Relationship_Notes, Terminology_Notes
2024-02-29 (CWE 4.14, 2024-02-29)	CWE Content Team	MITRE
2024-02-29 (CWE 4.14, 2024-02-29)	updated Observed_Examples
2023-10-26	CWE Content Team	MITRE
2023-10-26	updated Observed_Examples
2023-06-29	CWE Content Team	MITRE
2023-06-29	updated Mapping_Notes, Relationships
2023-04-27	CWE Content Team	MITRE
2023-04-27	updated Relationships, Taxonomy_Mappings
2023-01-31	CWE Content Team	MITRE
2023-01-31	updated Description, Detection_Factors
2022-10-13	CWE Content Team	MITRE
2022-10-13	updated Observed_Examples
2022-06-28	CWE Content Team	MITRE
2022-06-28	updated Observed_Examples, Relationships
2021-07-20	CWE Content Team	MITRE
2021-07-20	updated Relationships
2021-03-15	CWE Content Team	MITRE
2021-03-15	updated Potential_Mitigations
2020-12-10	CWE Content Team	MITRE
2020-12-10	updated Observed_Examples
2020-08-20	CWE Content Team	MITRE
2020-08-20	updated Relationships
2020-06-25	CWE Content Team	MITRE
2020-06-25	updated Observed_Examples
2020-02-24	CWE Content Team	MITRE
2020-02-24	updated Relationships
2019-09-19	CWE Content Team	MITRE
2019-09-19	updated Relationships
2019-01-03	CWE Content Team	MITRE
2019-01-03	updated Relationships
2018-03-27	CWE Content Team	MITRE
2018-03-27	updated References
2017-11-08	CWE Content Team	MITRE
2017-11-08	updated Functional_Areas, Observed_Examples, References, Taxonomy_Mappings
2017-01-19	CWE Content Team	MITRE
2017-01-19	updated Relationships
2015-12-07	CWE Content Team	MITRE
2015-12-07	updated Relationships
2014-07-30	CWE Content Team	MITRE
2014-07-30	updated Detection_Factors, Relationships, Taxonomy_Mappings
2013-07-17	CWE Content Team	MITRE
2013-07-17	updated References
2012-10-30	CWE Content Team	MITRE
2012-10-30	updated Potential_Mitigations
2012-05-11	CWE Content Team	MITRE
2012-05-11	updated Common_Consequences, Demonstrative_Examples, References, Relationships
2011-09-13	CWE Content Team	MITRE
2011-09-13	updated Potential_Mitigations, References, Relationships, Taxonomy_Mappings
2011-06-27	CWE Content Team	MITRE
2011-06-27	updated Relationships
2011-06-01	CWE Content Team	MITRE
2011-06-01	updated Common_Consequences
2010-09-27	CWE Content Team	MITRE
2010-09-27	updated Observed_Examples, Potential_Mitigations
2010-06-21	CWE Content Team	MITRE
2010-06-21	updated Common_Consequences, Potential_Mitigations, References
2010-04-05	CWE Content Team	MITRE
2010-04-05	updated Demonstrative_Examples, Detection_Factors, Potential_Mitigations, References, Related_Attack_Patterns
2010-02-16	CWE Content Team	MITRE
2010-02-16	updated Applicable_Platforms, Detection_Factors, Functional_Areas, Observed_Examples, Potential_Mitigations, References, Related_Attack_Patterns, Relationships, Taxonomy_Mappings, Terminology_Notes
2009-10-29	CWE Content Team	MITRE
2009-10-29	updated Relationships
2009-05-27	CWE Content Team	MITRE
2009-05-27	updated Demonstrative_Examples
2009-01-12	CWE Content Team	MITRE
2009-01-12	updated Description, Name
2008-11-24	CWE Content Team	MITRE
2008-11-24	updated Relationships, Taxonomy_Mappings
2008-10-14	CWE Content Team	MITRE
2008-10-14	updated Common_Consequences, Description, Potential_Mitigations, Terminology_Notes
2008-09-08	CWE Content Team	MITRE
2008-09-08	updated Common_Consequences, Relationships, Relationship_Notes, Taxonomy_Mappings, Terminology_Notes
Previous Entry Names
Change Date	Previous Entry Name
2009-01-12	Integer Overflow (Wrap or Wraparound)

Weakness ID: 772

View customized information:

Description

The product does not release a resource after its effective lifetime has ended, i.e., after the resource is no longer needed.

Extended Description

When a resource is not released after use, it can allow attackers to cause a denial of service by causing the allocation of resources without triggering their release. Frequently-affected resources include memory, CPU, disk space, power or battery, etc.

Common Consequences

Impact	Details
DoS: Resource Consumption (Other)	Scope: Availability An attacker that can influence the allocation of resources that are not properly released could deplete the available resource pool and prevent all other processes from accessing the same type of resource.

Potential Mitigations

Phase(s)	Mitigation
Requirements	Strategy: Language Selection Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, languages such as Java, Ruby, and Lisp perform automatic garbage collection that releases memory for objects that have been deallocated.
Implementation	It is good practice to be responsible for freeing all resources you allocate and to be consistent with how and where you free resources in a function. If you allocate resources that you intend to free upon completion of the function, you must be sure to free the resources at all exit points for that function including error conditions.
Operation; Architecture and Design	Strategy: Resource Limitation Use resource-limiting settings provided by the operating system or environment. For example, when managing system resources in POSIX, setrlimit() can be used to set limits for certain types of resources, and getrlimit() can determine how many resources are available. However, these functions are not available on all operating systems. When the current levels get close to the maximum that is defined for the application (see CWE-770), then limit the allocation of further resources to privileged users; alternately, begin releasing resources for less-privileged users. While this mitigation may protect the system from attack, it will not necessarily stop attackers from adversely impacting other users. Ensure that the application performs the appropriate error checks and error handling in case resources become unavailable (CWE-703).

Relationships

Relevant to the view "Research Concepts" (View-1000)

Nature	Type	ID	Name
ChildOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	404	Improper Resource Shutdown or Release
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	401	Missing Release of Memory after Effective Lifetime
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	775	Missing Release of File Descriptor or Handle after Effective Lifetime
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	1091	Use of Object without Invoking Destructor Method
CanFollow	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	911	Improper Update of Reference Count

Relevant to the view "Software Development" (View-699)

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	399	Resource Management Errors

Relevant to the view "Weaknesses for Simplified Mapping of Published Vulnerabilities" (View-1003)

Nature	Type	ID	Name
ChildOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	404	Improper Resource Shutdown or Release

Relevant to the view "CISQ Quality Measures (2020)" (View-1305)

Nature	Type	ID	Name
ChildOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	404	Improper Resource Shutdown or Release

Relevant to the view "CISQ Data Protection Measures" (View-1340)

Nature	Type	ID	Name
ChildOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	404	Improper Resource Shutdown or Release

Modes Of Introduction

Phase	Note
Implementation

Applicable Platforms

Technologies

Class: Mobile (Undetermined Prevalence)

Likelihood Of Exploit

High

Demonstrative Examples

Example 1

(bad code)

Example Language: Java

private void processFile(string fName)
{

BufferReader fil = new BufferReader(new FileReader(fName));
String line;
while ((line = fil.ReadLine()) != null)
{

processLine(line);

}

(good code)

Example Language: Java

private void processFile(string fName)
{

BufferReader fil = new BufferReader(new FileReader(fName));
String line;
while ((line = fil.ReadLine()) != null)
{

processLine(line);

}
fil.Close();

}

Example 2

The following code attempts to open a new connection to a database, process the results returned by the database, and close the allocated SqlConnection object.

(bad code)

Example Language: C#

SqlConnection conn = new SqlConnection(connString);
SqlCommand cmd = new SqlCommand(queryString);
cmd.Connection = conn;
conn.Open();
SqlDataReader rdr = cmd.ExecuteReader();
HarvestResults(rdr);
conn.Connection.Close();

The problem with the above code is that if an exception occurs while executing the SQL or processing the results, the SqlConnection object is not closed. If this happens often enough, the database will run out of available cursors and not be able to execute any more SQL queries.

Example 3

This code attempts to open a connection to a database and catches any exceptions that may occur.

(bad code)

Example Language: Java

try {

Connection con = DriverManager.getConnection(some_connection_string);

}
catch ( Exception e ) {

log( e );

}

Example 4

(bad code)

Example Language: C#

Example 5

The following C function does not close the file handle it opens if an error occurs. If the process is long-lived, the process can run out of file handles.

(bad code)

Example Language: C

int decodeFile(char* fName) {

char buf[BUF_SZ];
FILE* f = fopen(fName, "r");
if (!f) {

printf("cannot open %s\n", fName);
return DECODE_FAIL;

}
else {

while (fgets(buf, BUF_SZ, f)) {

if (!checkChecksum(buf)) {

return DECODE_FAIL;

}
else {

decodeBlock(buf);

}

}
fclose(f);
return DECODE_SUCCESS;

}

Selected Observed Examples

Reference	Description
CVE-2007-0897	Chain: anti-virus product encounters a malformed file but returns from a function without closing a file descriptor (CWE-775) leading to file descriptor consumption (CWE-400) and failed scans.
CVE-2001-0830	Sockets not properly closed when attacker repeatedly connects and disconnects from server.
CVE-1999-1127	Does not shut down named pipe connections if malformed data is sent.
CVE-2009-2858	Chain: memory leak (CWE-404) leads to resource exhaustion.
CVE-2009-2054	Product allows exhaustion of file descriptors when processing a large number of TCP packets.
CVE-2008-2122	Port scan triggers CPU consumption with processes that attempt to read data from closed sockets.
CVE-2007-4103	Product allows resource exhaustion via a large number of calls that do not complete a 3-way handshake.
CVE-2002-1372	Chain: Return values of file/socket operations are not checked (CWE-252), allowing resultant consumption of file descriptors (CWE-772).

Memberships

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	808	2010 Top 25 - Weaknesses On the Cusp
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	867	2011 Top 25 - Weaknesses On the Cusp
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	882	CERT C++ Secure Coding Section 14 - Concurrency (CON)
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	884	CWE Cross-section
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	982	SFP Secondary Cluster: Failure to Release Resource
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1129	CISQ Quality Measures (2016) - Reliability
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1131	CISQ Quality Measures (2016) - Security
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1162	SEI CERT C Coding Standard - Guidelines 08. Memory Management (MEM)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1163	SEI CERT C Coding Standard - Guidelines 09. Input Output (FIO)
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1200	Weaknesses in the 2019 CWE Top 25 Most Dangerous Software Errors
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1416	Comprehensive Categorization: Resource Lifecycle Management

Vulnerability Mapping Notes

Usage	ALLOWED (this CWE ID may be used to map to real-world vulnerabilities)
Reason	Acceptable-Use
Rationale	This CWE entry is at the Base level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.
Comments	Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction.

Notes

Theoretical

Maintenance

"Resource exhaustion" (CWE-400) is currently treated as a weakness, although it is more like a category of weaknesses that all have the same type of consequence. While this entry treats CWE-400 as a parent in view 1000, the relationship is probably more appropriately described as a chain.

Taxonomy Mappings

Mapped Taxonomy Name	Node ID	Fit	Mapped Node Name
CERT C Secure Coding	FIO42-C	CWE More Abstract	Close files when they are no longer needed
CERT C Secure Coding	MEM31-C	CWE More Abstract	Free dynamically allocated memory when no longer needed
OMG ASCSM	ASCSM-CWE-772
OMG ASCRM	ASCRM-CWE-772
Software Fault Patterns	SFP14		Failure to Release Resource

Related Attack Patterns

CAPEC-ID	Attack Pattern Name
CAPEC-469	HTTP DoS

References

[REF-961]	Object Management Group (OMG). "Automated Source Code Reliability Measure (ASCRM)". ASCRM-CWE-772. 2016-01. <http://www.omg.org/spec/ASCRM/1.0/>.
[REF-962]	Object Management Group (OMG). "Automated Source Code Security Measure (ASCSM)". ASCSM-CWE-772. 2016-01. <http://www.omg.org/spec/ASCSM/1.0/>.

Content History

Submissions
Submission Date	Submitter	Organization
2009-05-13 (CWE 1.4, 2009-05-27)	CWE Content Team	MITRE
2009-05-13 (CWE 1.4, 2009-05-27)
Modifications
Modification Date	Modifier	Organization
2023-10-26	CWE Content Team	MITRE
2023-10-26	updated Observed_Examples
2023-06-29	CWE Content Team	MITRE
2023-06-29	updated Mapping_Notes
2023-04-27	CWE Content Team	MITRE
2023-04-27	updated Relationships, Time_of_Introduction
2023-01-31	CWE Content Team	MITRE
2023-01-31	updated Description
2022-10-13	CWE Content Team	MITRE
2022-10-13	updated Relationships, Taxonomy_Mappings
2021-03-15	CWE Content Team	MITRE
2021-03-15	updated Demonstrative_Examples
2020-12-10	CWE Content Team	MITRE
2020-12-10	updated Relationships
2020-08-20	CWE Content Team	MITRE
2020-08-20	updated Relationships
2020-02-24	CWE Content Team	MITRE
2020-02-24	updated Applicable_Platforms, Relationships, Taxonomy_Mappings
2019-09-19	CWE Content Team	MITRE
2019-09-19	updated Description, Relationships
2019-06-20	CWE Content Team	MITRE
2019-06-20	updated Relationships
2019-01-03	CWE Content Team	MITRE
2019-01-03	updated Common_Consequences, References, Relationships, Taxonomy_Mappings
2017-11-08	CWE Content Team	MITRE
2017-11-08	updated Likelihood_of_Exploit, Taxonomy_Mappings
2017-01-19	CWE Content Team	MITRE
2017-01-19	updated Relationships
2014-07-30	CWE Content Team	MITRE
2014-07-30	updated Relationships, Taxonomy_Mappings
2014-02-18	CWE Content Team	MITRE
2014-02-18	updated Applicable_Platforms, Demonstrative_Examples
2013-02-21	CWE Content Team	MITRE
2013-02-21	updated Relationships
2012-10-30	CWE Content Team	MITRE
2012-10-30	updated Potential_Mitigations
2012-05-11	CWE Content Team	MITRE
2012-05-11	updated Demonstrative_Examples, Relationships, Taxonomy_Mappings
2011-09-13	CWE Content Team	MITRE
2011-09-13	updated Relationships, Taxonomy_Mappings
2011-06-27	CWE Content Team	MITRE
2011-06-27	updated Observed_Examples, Related_Attack_Patterns, Relationships
2011-06-01	CWE Content Team	MITRE
2011-06-01	updated Common_Consequences, Relationships, Taxonomy_Mappings
2010-06-21	CWE Content Team	MITRE
2010-06-21	updated Potential_Mitigations
2010-04-05	CWE Content Team	MITRE
2010-04-05	updated Potential_Mitigations
2010-02-16	CWE Content Team	MITRE
2010-02-16	updated Demonstrative_Examples, Potential_Mitigations, Relationships

Weakness ID: 476

View customized information:

Description

The product dereferences a pointer that it expects to be valid but is NULL.

Alternate Terms

NPD	Common abbreviation for Null Pointer Dereference
null deref	Common abbreviation for Null Pointer Dereference
NPE	Common abbreviation for Null Pointer Exception
nil pointer dereference	used for access of nil in Go programs

Common Consequences

Impact	Details
DoS: Crash, Exit, or Restart	Scope: Availability NULL pointer dereferences usually result in the failure of the process unless exception handling (on some platforms) is available and implemented. Even when exception handling is being used, it can still be very difficult to return the software to a safe state of operation.
Execute Unauthorized Code or Commands; Read Memory; Modify Memory	Scope: Integrity, Confidentiality In rare circumstances, when NULL is equivalent to the 0x0 memory address and privileged code can access it, then writing or reading memory is possible, which may lead to code execution.

Potential Mitigations

Phase(s)	Mitigation
Implementation	For any pointers that could have been modified or provided from a function that can return NULL, check the pointer for NULL before use. When working with a multithreaded or otherwise asynchronous environment, ensure that proper locking APIs are used to lock before the check, and unlock when it has finished.
Requirements	Select a programming language that is not susceptible to these issues.
Implementation	Check the results of all functions that return a value and verify that the value is non-null before acting upon it. Effectiveness: Moderate Note: Checking the return value of the function will typically be sufficient, however beware of race conditions (CWE-362) in a concurrent environment. This solution does not handle the use of improperly initialized variables (CWE-665).
Architecture and Design	Identify all variables and data stores that receive information from external sources, and apply input validation to make sure that they are only initialized to expected values.
Implementation	Explicitly initialize all variables and other data stores, either during declaration or just before the first usage.

Relationships

Relevant to the view "Research Concepts" (View-1000)

Nature	Type	ID	Name
ChildOf	Pillar - a weakness that is the most abstract type of weakness and represents a theme for all class/base/variant weaknesses related to it. A Pillar is different from a Category as a Pillar is still technically a type of weakness that describes a mistake, while a Category represents a common characteristic used to group related things.	710	Improper Adherence to Coding Standards
ChildOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	754	Improper Check for Unusual or Exceptional Conditions
CanFollow	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	252	Unchecked Return Value
CanFollow	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	362	Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
CanFollow	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	789	Memory Allocation with Excessive Size Value
CanFollow	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	1325	Improperly Controlled Sequential Memory Allocation

Relevant to the view "Software Development" (View-699)

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	465	Pointer Issues

Relevant to the view "Weaknesses for Simplified Mapping of Published Vulnerabilities" (View-1003)

Nature	Type	ID	Name
ChildOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	754	Improper Check for Unusual or Exceptional Conditions

Modes Of Introduction

Phase	Note
Implementation

Applicable Platforms

Languages

C (Undetermined Prevalence)

C++ (Undetermined Prevalence)

Java (Undetermined Prevalence)

C# (Undetermined Prevalence)

Go (Undetermined Prevalence)

Likelihood Of Exploit

Medium

Demonstrative Examples

Example 1

This example takes an IP address from a user, verifies that it is well formed and then looks up the hostname and copies it into a buffer.

(bad code)

Example Language: C

void host_lookup(char *user_supplied_addr){

}

Note that this code is also vulnerable to a buffer overflow (CWE-119).

Example 2

In the following code, the programmer assumes that the system always has a property named "cmd" defined. If an attacker can control the program's environment so that "cmd" is not defined, the program throws a NULL pointer exception when it attempts to call the trim() method.

(bad code)

Example Language: Java

String cmd = System.getProperty("cmd");
cmd = cmd.trim();

Example 3

This Android application has registered to handle a URL when sent an intent:

(bad code)

Example Language: Java

@Override
public void onReceive(Context context, Intent intent) {

if("com.example.URLHandler.openURL".equals(intent.getAction())) {

String URL = intent.getStringExtra("URLToOpen");
int length = URL.length();

...
}

}

Example 4

Consider the following example of a typical client server exchange. The HandleRequest function is intended to perform a request and use a defer to close the connection whenever the function returns.

(bad code)

Example Language: Go

func HandleRequest(client http.Client, request *http.Request) (*http.Response, error) {

response, err := client.Do(request)
defer response.Body.Close()
if err != nil {

return nil, err

}
...

}

If a user supplies a malformed request or violates the client policy, the Do method can return a nil response and a non-nil err.

This HandleRequest Function evaluates the close before checking the error. A deferred call's arguments are evaluated immediately, so the defer statement panics due to a nil response.

Selected Observed Examples

Reference	Description
CVE-2005-3274	race condition causes a table to be corrupted if a timer activates while it is being modified, leading to resultant NULL dereference; also involves locking.
CVE-2002-1912	large number of packets leads to NULL dereference
CVE-2005-0772	packet with invalid error status value triggers NULL dereference
CVE-2009-4895	Chain: race condition for an argument value, possibly resulting in NULL dereference
CVE-2020-29652	ssh component for Go allows clients to cause a denial of service (nil pointer dereference) against SSH servers.
CVE-2009-2692	Chain: Use of an unimplemented network socket operation pointing to an uninitialized handler function (CWE-456) causes a crash because of a null pointer dereference (CWE-476).
CVE-2009-3547	Chain: race condition (CWE-362) might allow resource to be released before operating on it, leading to NULL dereference (CWE-476)
CVE-2009-3620	Chain: some unprivileged ioctls do not verify that a structure has been initialized before invocation, leading to NULL dereference
CVE-2009-2698	Chain: IP and UDP layers each track the same value with different mechanisms that can get out of sync, possibly resulting in a NULL dereference
CVE-2009-2692	Chain: uninitialized function pointers can be dereferenced allowing code execution
CVE-2009-0949	Chain: improper initialization of memory can lead to NULL dereference
CVE-2008-3597	Chain: game server can access player data structures before initialization has happened leading to NULL dereference
CVE-2020-6078	Chain: The return value of a function returning a pointer is not checked for success (CWE-252) resulting in the later use of an uninitialized variable (CWE-456) and a null pointer dereference (CWE-476)
CVE-2008-0062	Chain: a message having an unknown message type may cause a reference to uninitialized memory resulting in a null pointer dereference (CWE-476) or dangling pointer (CWE-825), possibly crashing the system or causing heap corruption.
CVE-2008-5183	Chain: unchecked return value can lead to NULL dereference
CVE-2004-0079	SSL software allows remote attackers to cause a denial of service (crash) via a crafted SSL/TLS handshake that triggers a null dereference.
CVE-2004-0365	Network monitor allows remote attackers to cause a denial of service (crash) via a malformed RADIUS packet that triggers a null dereference.
CVE-2003-1013	Network monitor allows remote attackers to cause a denial of service (crash) via a malformed Q.931, which triggers a null dereference.
CVE-2003-1000	Chat client allows remote attackers to cause a denial of service (crash) via a passive DCC request with an invalid ID number, which causes a null dereference.
CVE-2004-0389	Server allows remote attackers to cause a denial of service (crash) via malformed requests that trigger a null dereference.
CVE-2004-0119	OS allows remote attackers to cause a denial of service (crash from null dereference) or execute arbitrary code via a crafted request during authentication protocol selection.
CVE-2004-0458	Game allows remote attackers to cause a denial of service (server crash) via a missing argument, which triggers a null pointer dereference.
CVE-2002-0401	Network monitor allows remote attackers to cause a denial of service (crash) or execute arbitrary code via malformed packets that cause a NULL pointer dereference.
CVE-2001-1559	Chain: System call returns wrong value (CWE-393), leading to a resultant NULL dereference (CWE-476).

Weakness Ordinalities

Ordinality	Description
Resultant	(where the weakness is typically related to the presence of some other weaknesses) NULL pointer dereferences are frequently resultant from rarely encountered error conditions and race conditions, since these are most likely to escape detection during the testing phases.

Detection Methods

Method	Details
Automated Dynamic Analysis	This weakness can be detected using dynamic tools and techniques that interact with the software using large test suites with many diverse inputs, such as fuzz testing (fuzzing), robustness testing, and fault injection. The software's operation may slow down, but it should not become unstable, crash, or generate incorrect results. Effectiveness: Moderate
Manual Dynamic Analysis	Identify error conditions that are not likely to occur during normal usage and trigger them. For example, run the program under low memory conditions, run with insufficient privileges or permissions, interrupt a transaction before it is completed, or disable connectivity to basic network services such as DNS. Monitor the software for any unexpected behavior. If you trigger an unhandled exception or similar error that was discovered and handled by the application's environment, it may still indicate unexpected conditions that were not handled by the application itself.
Automated Static Analysis	Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.) Effectiveness: High

Memberships

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	398	7PK - Code Quality
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	730	OWASP Top Ten 2004 Category A9 - Denial of Service
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	737	CERT C Secure Coding Standard (2008) Chapter 4 - Expressions (EXP)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	742	CERT C Secure Coding Standard (2008) Chapter 9 - Memory Management (MEM)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	808	2010 Top 25 - Weaknesses On the Cusp
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	867	2011 Top 25 - Weaknesses On the Cusp
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	871	CERT C++ Secure Coding Section 03 - Expressions (EXP)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	876	CERT C++ Secure Coding Section 08 - Memory Management (MEM)
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	884	CWE Cross-section
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	971	SFP Secondary Cluster: Faulty Pointer Use
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1136	SEI CERT Oracle Secure Coding Standard for Java - Guidelines 02. Expressions (EXP)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1157	SEI CERT C Coding Standard - Guidelines 03. Expressions (EXP)
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1200	Weaknesses in the 2019 CWE Top 25 Most Dangerous Software Errors
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1306	CISQ Quality Measures - Reliability
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1337	Weaknesses in the 2021 CWE Top 25 Most Dangerous Software Weaknesses
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1350	Weaknesses in the 2020 CWE Top 25 Most Dangerous Software Weaknesses
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1387	Weaknesses in the 2022 CWE Top 25 Most Dangerous Software Weaknesses
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1412	Comprehensive Categorization: Poor Coding Practices
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1425	Weaknesses in the 2023 CWE Top 25 Most Dangerous Software Weaknesses
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1430	Weaknesses in the 2024 CWE Top 25 Most Dangerous Software Weaknesses

Vulnerability Mapping Notes

Usage	ALLOWED (this CWE ID may be used to map to real-world vulnerabilities)
Reason	Acceptable-Use
Rationale	This CWE entry is at the Base level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.
Comments	Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction.

Taxonomy Mappings

Mapped Taxonomy Name	Node ID	Fit	Mapped Node Name
7 Pernicious Kingdoms			Null Dereference
CLASP			Null-pointer dereference
PLOVER			Null Dereference (Null Pointer Dereference)
OWASP Top Ten 2004	A9	CWE More Specific	Denial of Service
CERT C Secure Coding	EXP34-C	Exact	Do not dereference null pointers
Software Fault Patterns	SFP7		Faulty Pointer Use

References

[REF-6]	Katrina Tsipenyuk, Brian Chess and Gary McGraw. "Seven Pernicious Kingdoms: A Taxonomy of Software Security Errors". NIST Workshop on Software Security Assurance Tools Techniques and Metrics. NIST. 2005-11-07. <https://samate.nist.gov/SSATTM_Content/papers/Seven%20Pernicious%20Kingdoms%20-%20Taxonomy%20of%20Sw%20Security%20Errors%20-%20Tsipenyuk%20-%20Chess%20-%20McGraw.pdf>.
[REF-18]	Secure Software, Inc.. "The CLASP Application Security Process". 2005. <https://cwe.mitre.org/documents/sources/TheCLASPApplicationSecurityProcess.pdf>. (URL validated: 2024-11-17)
[REF-1031]	"Null pointer / Null dereferencing". Wikipedia. 2019-07-15. <https://en.wikipedia.org/wiki/Null_pointer#Null_dereferencing>.
[REF-1032]	"Null Reference Creation and Null Pointer Dereference". Apple. <https://developer.apple.com/documentation/xcode/null-reference-creation-and-null-pointer-dereference>. (URL validated: 2023-04-07)
[REF-1033]	"NULL Pointer Dereference [CWE-476]". ImmuniWeb. 2012-09-11. <https://www.immuniweb.com/vulnerability/null-pointer-dereference.html>.

Content History

Submissions
Submission Date	Submitter	Organization
2006-07-19 (CWE Draft 3, 2006-07-19)	7 Pernicious Kingdoms
2006-07-19 (CWE Draft 3, 2006-07-19)
Contributions
Contribution Date	Contributor	Organization
2024-02-29 (CWE 4.15, 2024-07-16)	Abhi Balakrishnan
2024-02-29 (CWE 4.15, 2024-07-16)	Provided diagram to improve CWE usability
Modifications
Modification Date	Modifier	Organization
2025-04-03 (CWE 4.17, 2025-04-03)	CWE Content Team	MITRE
2025-04-03 (CWE 4.17, 2025-04-03)	updated Demonstrative_Examples, Potential_Mitigations
2024-11-19 (CWE 4.16, 2024-11-19)	CWE Content Team	MITRE
2024-11-19 (CWE 4.16, 2024-11-19)	updated Relationships
2024-07-16 (CWE 4.15, 2024-07-16)	CWE Content Team	MITRE
2024-07-16 (CWE 4.15, 2024-07-16)	updated Alternate_Terms, Demonstrative_Examples, Description, Diagram, Potential_Mitigations, Relationships, Weakness_Ordinalities
2023-10-26	CWE Content Team	MITRE
2023-10-26	updated Observed_Examples
2023-06-29	CWE Content Team	MITRE
2023-06-29	updated Mapping_Notes, Relationships
2023-04-27	CWE Content Team	MITRE
2023-04-27	updated Demonstrative_Examples, Detection_Factors, References, Relationships
2022-10-13	CWE Content Team	MITRE
2022-10-13	updated Alternate_Terms, Applicable_Platforms, Observed_Examples
2022-06-28	CWE Content Team	MITRE
2022-06-28	updated Relationships
2022-04-28	CWE Content Team	MITRE
2022-04-28	updated Alternate_Terms
2021-07-20	CWE Content Team	MITRE
2021-07-20	updated Relationships
2021-03-15	CWE Content Team	MITRE
2021-03-15	updated Demonstrative_Examples, Observed_Examples
2020-12-10	CWE Content Team	MITRE
2020-12-10	updated Relationships
2020-08-20	CWE Content Team	MITRE
2020-08-20	updated Relationships
2020-06-25	CWE Content Team	MITRE
2020-06-25	updated Common_Consequences
2020-02-24	CWE Content Team	MITRE
2020-02-24	updated References
2019-09-19	CWE Content Team	MITRE
2019-09-19	updated References, Relationships
2019-06-20	CWE Content Team	MITRE
2019-06-20	updated Relationships
2019-01-03	CWE Content Team	MITRE
2019-01-03	updated Relationships
2017-11-08	CWE Content Team	MITRE
2017-11-08	updated Relationships, Taxonomy_Mappings, White_Box_Definitions
2017-01-19	CWE Content Team	MITRE
2017-01-19	updated Relationships
2015-12-07	CWE Content Team	MITRE
2015-12-07	updated Relationships
2014-07-30	CWE Content Team	MITRE
2014-07-30	updated Relationships, Taxonomy_Mappings
2014-02-18	CWE Content Team	MITRE
2014-02-18	updated Demonstrative_Examples
2012-05-11	CWE Content Team	MITRE
2012-05-11	updated Observed_Examples, Related_Attack_Patterns, Relationships
2011-09-13	CWE Content Team	MITRE
2011-09-13	updated Relationships, Taxonomy_Mappings
2011-06-27	CWE Content Team	MITRE
2011-06-27	updated Related_Attack_Patterns, Relationships
2011-06-01	CWE Content Team	MITRE
2011-06-01	updated Common_Consequences
2010-12-13	CWE Content Team	MITRE
2010-12-13	updated Relationships
2010-09-27	CWE Content Team	MITRE
2010-09-27	updated Demonstrative_Examples, Observed_Examples, Relationships
2010-06-21	CWE Content Team	MITRE
2010-06-21	updated Demonstrative_Examples, Description, Detection_Factors, Potential_Mitigations
2010-02-16	CWE Content Team	MITRE
2010-02-16	updated Potential_Mitigations, Relationships
2009-12-28	CWE Content Team	MITRE
2009-12-28	updated Common_Consequences, Demonstrative_Examples, Other_Notes, Potential_Mitigations, Weakness_Ordinalities
2009-10-29	CWE Content Team	MITRE
2009-10-29	updated Relationships
2009-05-27	CWE Content Team	MITRE
2009-05-27	updated Demonstrative_Examples
2008-11-24	CWE Content Team	MITRE
2008-11-24	updated Relationships, Taxonomy_Mappings
2008-09-08	CWE Content Team	MITRE
2008-09-08	updated Applicable_Platforms, Common_Consequences, Relationships, Other_Notes, Taxonomy_Mappings, Weakness_Ordinalities
2008-08-01		KDM Analytics
2008-08-01	added/updated white box definitions
2008-07-01	Eric Dalci	Cigital
2008-07-01	updated Time_of_Introduction

Weakness ID: 193

View customized information:

Description

A product calculates or uses an incorrect maximum or minimum value that is 1 more, or 1 less, than the correct value.

Alternate Terms

off-by-five

An "off-by-five" error was reported for sudo in 2002 (CVE-2002-0184), but that is more like a "length calculation" error.

Common Consequences

Impact	Details
DoS: Crash, Exit, or Restart; DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory); DoS: Instability	Scope: Availability This weakness will generally lead to undefined behavior and therefore crashes. In the case of overflows involving loop index variables, the likelihood of infinite loops is also high.
Modify Memory	Scope: Integrity If the value in question is important to data (as opposed to flow), simple data corruption has occurred. Also, if the wrap around results in other conditions such as buffer overflows, further memory corruption may occur.
Execute Unauthorized Code or Commands; Bypass Protection Mechanism	Scope: Confidentiality, Availability, Access Control This weakness can sometimes trigger buffer overflows which can be used to execute arbitrary code. This is usually outside the scope of a program's implicit security policy.

Potential Mitigations

Phase(s)	Mitigation
Implementation	When copying character arrays or using character manipulation methods, the correct size parameter must be used to account for the null terminator that needs to be added at the end of the array. Some examples of functions susceptible to this weakness in C include strcpy(), strncpy(), strcat(), strncat(), printf(), sprintf(), scanf() and sscanf().

Relationships

Relevant to the view "Research Concepts" (View-1000)

Nature	Type	ID	Name
ChildOf	Pillar - a weakness that is the most abstract type of weakness and represents a theme for all class/base/variant weaknesses related to it. A Pillar is different from a Category as a Pillar is still technically a type of weakness that describes a mistake, while a Category represents a common characteristic used to group related things.	682	Incorrect Calculation
CanPrecede	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	119	Improper Restriction of Operations within the Bounds of a Memory Buffer
CanPrecede	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	170	Improper Null Termination
CanPrecede	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	617	Reachable Assertion

Relevant to the view "Software Development" (View-699)

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	189	Numeric Errors

Relevant to the view "Weaknesses for Simplified Mapping of Published Vulnerabilities" (View-1003)

Nature	Type	ID	Name
ChildOf	Pillar - a weakness that is the most abstract type of weakness and represents a theme for all class/base/variant weaknesses related to it. A Pillar is different from a Category as a Pillar is still technically a type of weakness that describes a mistake, while a Category represents a common characteristic used to group related things.	682	Incorrect Calculation

Modes Of Introduction

Phase	Note
Implementation

Applicable Platforms

Languages

C (Undetermined Prevalence)

Class: Not Language-Specific (Undetermined Prevalence)

Demonstrative Examples

Example 1

(bad code)

Example Language: C

int i;
unsigned int numWidgets;
Widget **WidgetList;

numWidgets = GetUntrustedSizeValue();
if ((numWidgets == 0) || (numWidgets > MAX_NUM_WIDGETS)) {

ExitError("Incorrect number of widgets requested!");

}
WidgetList = (Widget **)malloc(numWidgets * sizeof(Widget *));
printf("WidgetList ptr=%p\n", WidgetList);
for(i=0; i<numWidgets; i++) {

WidgetList[i] = InitializeWidget();

}
WidgetList[numWidgets] = NULL;
showWidgets(WidgetList);

Example 2

In this example, the code does not account for the terminating null character, and it writes one byte beyond the end of the buffer.

The first call to strncat() appends up to 20 characters plus a terminating null character to fullname[]. There is plenty of allocated space for this, and there is no weakness associated with this first call. However, the second call to strncat() potentially appends another 20 characters. The code does not account for the terminating null character that is automatically added by strncat(). This terminating null character would be written one byte beyond the end of the fullname[] buffer. Therefore an off-by-one error exists with the second strncat() call, as the third argument should be 19.

(bad code)

Example Language: C

char firstname[20];
char lastname[20];
char fullname[40];

fullname[0] = '\0';

strncat(fullname, firstname, 20);
strncat(fullname, lastname, 20);

When using a function like strncat() one must leave a free byte at the end of the buffer for a terminating null character, thus avoiding the off-by-one weakness. Additionally, the last argument to strncat() is the number of characters to append, which must be less than the remaining space in the buffer. Be careful not to just use the total size of the buffer.

(good code)

Example Language: C

char firstname[20];
char lastname[20];
char fullname[40];

fullname[0] = '\0';

strncat(fullname, firstname, sizeof(fullname)-strlen(fullname)-1);
strncat(fullname, lastname, sizeof(fullname)-strlen(fullname)-1);

Example 3

The Off-by-one error can also be manifested when reading characters from a character array within a for loop that has an incorrect continuation condition.

(bad code)

Example Language: C

#define PATH_SIZE 60

char filename[PATH_SIZE];

for(i=0; i<=PATH_SIZE; i++) {

char c = fgetc(stdin);
if (c == EOF) {

filename[i] = '\0';

}
else {

filename[i] = c;

}

If i reaches PATH_SIZE, then the loop continues. However, filename[PATH_SIZE] is actually out of bounds, since the valid index range is from 0 to PATH_SIZE-1.

In this case, the correct continuation condition is shown below.

(good code)

Example Language: C

for(i=0; i<PATH_SIZE; i++) {
...

Example 4

As another example the Off-by-one error can occur when using the sprintf library function to copy a string variable to a formatted string variable and the original string variable comes from an untrusted source. As in the following example where a local function, setFilename is used to store the value of a filename to a database but first uses sprintf to format the filename. The setFilename function includes an input parameter with the name of the file that is used as the copy source in the sprintf function. The sprintf function will copy the file name to a char array of size 20 and specifies the format of the new variable as 16 characters followed by the file extension .dat.

(bad code)

Example Language: C

int setFilename(char *filename) {

char name[20];
sprintf(name, "%16s.dat", filename);
int success = saveFormattedFilenameToDB(name);
return success;

}

However this will cause an Off-by-one error if the original filename is exactly 16 characters or larger because the format of 16 characters with the file extension is exactly 20 characters and does not take into account the required null terminator that will be placed at the end of the string.

Selected Observed Examples

Reference	Description
CVE-2003-0252	Off-by-one error allows remote attackers to cause a denial of service and possibly execute arbitrary code via requests that do not contain newlines.
CVE-2001-1391	Off-by-one vulnerability in driver allows users to modify kernel memory.
CVE-2002-0083	Off-by-one error allows local users or remote malicious servers to gain privileges.
CVE-2002-0653	Off-by-one buffer overflow in function usd by server allows local users to execute arbitrary code as the server user via .htaccess files with long entries.
CVE-2002-0844	Off-by-one buffer overflow in version control system allows local users to execute arbitrary code.
CVE-1999-1568	Off-by-one error in FTP server allows a remote attacker to cause a denial of service (crash) via a long PORT command.
CVE-2004-0346	Off-by-one buffer overflow in FTP server allows local users to gain privileges via a 1024 byte RETR command.
CVE-2004-0005	Multiple buffer overflows in chat client allow remote attackers to cause a denial of service and possibly execute arbitrary code.
CVE-2003-0356	Multiple off-by-one vulnerabilities in product allow remote attackers to cause a denial of service and possibly execute arbitrary code.
CVE-2001-1496	Off-by-one buffer overflow in server allows remote attackers to cause a denial of service and possibly execute arbitrary code.
CVE-2004-0342	This is an interesting example that might not be an off-by-one.
CVE-2001-0609	An off-by-one enables a terminating null to be overwritten, which causes 2 strings to be merged and enable a format string.
CVE-2002-1745	Off-by-one error allows source code disclosure of files with 4 letter extensions that match an accepted 3-letter extension.
CVE-2002-1816	Off-by-one buffer overflow.
CVE-2002-1721	Off-by-one error causes an snprintf call to overwrite a critical internal variable with a null value.
CVE-2003-0466	Off-by-one error in function used in many products leads to a buffer overflow during pathname management, as demonstrated using multiple commands in an FTP server.
CVE-2003-0625	Off-by-one error allows read of sensitive memory via a malformed request.
CVE-2006-4574	Chain: security monitoring product has an off-by-one error that leads to unexpected length values, triggering an assertion.

Detection Methods

Method

Details

Automated Static Analysis

Effectiveness: High

Memberships

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	741	CERT C Secure Coding Standard (2008) Chapter 8 - Characters and Strings (STR)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	875	CERT C++ Secure Coding Section 07 - Characters and Strings (STR)
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	884	CWE Cross-section
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	977	SFP Secondary Cluster: Design
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1408	Comprehensive Categorization: Incorrect Calculation

Vulnerability Mapping Notes

Usage	ALLOWED (this CWE ID may be used to map to real-world vulnerabilities)
Reason	Acceptable-Use
Rationale	This CWE entry is at the Base level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.
Comments	Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction.

Notes

Relationship

This is not always a buffer overflow. For example, an off-by-one error could be a factor in a partial comparison, a read from the wrong memory location, an incorrect conditional, etc.

Taxonomy Mappings

Mapped Taxonomy Name	Node ID	Fit	Mapped Node Name
PLOVER			Off-by-one Error
CERT C Secure Coding	STR31-C		Guarantee that storage for strings has sufficient space for character data and the null terminator

References

[REF-155]	Halvar Flake. "Third Generation Exploits". presentation at Black Hat Europe 2001. <https://view.officeapps.live.com/op/view.aspx?src=https%3A%2F%2Fwww.blackhat.com%2Fpresentations%2Fbh-europe-01%2Fhalvar-flake%2Fbh-europe-01-halvarflake.ppt&wdOrigin=BROWSELINK>. (URL validated: 2023-04-07)
[REF-156]	Steve Christey. "Off-by-one errors: a brief explanation". Secprog and SC-L mailing list posts. 2004-05-05. <http://marc.info/?l=secprog&m=108379742110553&w=2>.
[REF-157]	klog. "The Frame Pointer Overwrite". Phrack Issue 55, Chapter 8. 1999-09-09. <https://kaizo.org/mirrors/phrack/phrack55/P55-08>. (URL validated: 2023-04-07)
[REF-140]	Greg Hoglund and Gary McGraw. "Exploiting Software: How to Break Code". Chapter 7, "Buffer Overflow". Addison-Wesley. 2004-02-27. <https://www.amazon.com/Exploiting-Software-How-Break-Code/dp/0201786958>. (URL validated: 2023-04-07)
[REF-44]	Michael Howard, David LeBlanc and John Viega. "24 Deadly Sins of Software Security". "Sin 5: Buffer Overruns." Page 89. McGraw-Hill. 2010.
[REF-62]	Mark Dowd, John McDonald and Justin Schuh. "The Art of Software Security Assessment". Chapter 5, "Off-by-One Errors", Page 180. 1st Edition. Addison Wesley. 2006.

Content History

Submissions
Submission Date	Submitter	Organization
2006-07-19 (CWE Draft 3, 2006-07-19)	PLOVER
2006-07-19 (CWE Draft 3, 2006-07-19)
Contributions
Contribution Date	Contributor	Organization
2024-07-20 (CWE 4.17, 2025-04-03)	Jason Xu
2024-07-20 (CWE 4.17, 2025-04-03)	Reported compilation error with demonstrative example.
Modifications
Modification Date	Modifier	Organization
2025-04-03 (CWE 4.17, 2025-04-03)	CWE Content Team	MITRE
2025-04-03 (CWE 4.17, 2025-04-03)	updated Applicable_Platforms, Demonstrative_Examples
2023-06-29	CWE Content Team	MITRE
2023-06-29	updated Mapping_Notes
2023-04-27	CWE Content Team	MITRE
2023-04-27	updated Detection_Factors, References, Relationships
2022-04-28	CWE Content Team	MITRE
2022-04-28	updated Research_Gaps
2021-03-15	CWE Content Team	MITRE
2021-03-15	updated Demonstrative_Examples
2020-02-24	CWE Content Team	MITRE
2020-02-24	updated Relationships
2019-06-20	CWE Content Team	MITRE
2019-06-20	updated Demonstrative_Examples, Relationships
2018-03-27	CWE Content Team	MITRE
2018-03-27	updated Demonstrative_Examples
2017-11-08	CWE Content Team	MITRE
2017-11-08	updated Applicable_Platforms, References, Taxonomy_Mappings
2017-05-03	CWE Content Team	MITRE
2017-05-03	updated Demonstrative_Examples
2014-07-30	CWE Content Team	MITRE
2014-07-30	updated Demonstrative_Examples, Relationships
2014-06-23	CWE Content Team	MITRE
2014-06-23	updated References
2012-05-11	CWE Content Team	MITRE
2012-05-11	updated Common_Consequences, Observed_Examples, References, Relationships
2011-09-13	CWE Content Team	MITRE
2011-09-13	updated Relationships, Taxonomy_Mappings
2011-06-27	CWE Content Team	MITRE
2011-06-27	updated Common_Consequences
2011-06-01	CWE Content Team	MITRE
2011-06-01	updated Common_Consequences
2010-12-13	CWE Content Team	MITRE
2010-12-13	updated Demonstrative_Examples
2010-02-16	CWE Content Team	MITRE
2010-02-16	updated Demonstrative_Examples
2009-12-28	CWE Content Team	MITRE
2009-12-28	updated Demonstrative_Examples, Potential_Mitigations
2008-11-24	CWE Content Team	MITRE
2008-11-24	updated Relationships, Taxonomy_Mappings
2008-09-08	CWE Content Team	MITRE
2008-09-08	updated Alternate_Terms, Common_Consequences, Relationships, Observed_Example, Relationship_Notes, Taxonomy_Mappings

Weakness ID: 807

View customized information:

Description

The product uses a protection mechanism that relies on the existence or values of an input, but the input can be modified by an untrusted actor in a way that bypasses the protection mechanism.

Extended Description

Developers may assume that inputs such as cookies, environment variables, and hidden form fields cannot be modified. However, an attacker could change these inputs using customized clients or other attacks. This change might not be detected. When security decisions such as authentication and authorization are made based on the values of these inputs, attackers can bypass the security of the software.

Without sufficient encryption, integrity checking, or other mechanism, any input that originates from an outsider cannot be trusted.

Common Consequences

Impact

Details

Bypass Protection Mechanism; Gain Privileges or Assume Identity; Varies by Context

Scope: Confidentiality, Access Control, Availability, Other

Attackers can bypass the security decision to access whatever is being protected. The consequences will depend on the associated functionality, but they can range from granting additional privileges to untrusted users to bypassing important security checks. Ultimately, this weakness may lead to exposure or modification of sensitive data, system crash, or execution of arbitrary code.

Potential Mitigations

Phase(s)	Mitigation
Architecture and Design	Strategy: Attack Surface Reduction Store state information and sensitive data on the server side only. Ensure that the system definitively and unambiguously keeps track of its own state and user state and has rules defined for legitimate state transitions. Do not allow any application user to affect state directly in any way other than through legitimate actions leading to state transitions. If information must be stored on the client, do not do so without encryption and integrity checking, or otherwise having a mechanism on the server side to catch tampering. Use a message authentication code (MAC) algorithm, such as Hash Message Authentication Code (HMAC) [REF-529]. Apply this against the state or sensitive data that has to be exposed, which can guarantee the integrity of the data - i.e., that the data has not been modified. Ensure that a strong hash function is used (CWE-328).
Architecture and Design	Strategy: Libraries or Frameworks Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. With a stateless protocol such as HTTP, use a framework that maintains the state for you. Examples include ASP.NET View State [REF-756] and the OWASP ESAPI Session Management feature [REF-45]. Be careful of language features that provide state support, since these might be provided as a convenience to the programmer and may not be considering security.
Architecture and Design	For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.
Operation; Implementation	Strategy: Environment Hardening When using PHP, configure the application so that it does not use register_globals. During implementation, develop the application so that it does not rely on this feature, but be wary of implementing a register_globals emulation that is subject to weaknesses such as CWE-95, CWE-621, and similar issues.
Architecture and Design; Implementation	Strategy: Attack Surface Reduction Understand all the potential areas where untrusted inputs can enter your software: parameters or arguments, cookies, anything read from the network, environment variables, reverse DNS lookups, query results, request headers, URL components, e-mail, files, filenames, databases, and any external systems that provide data to the application. Remember that such inputs may be obtained indirectly through API calls. Identify all inputs that are used for security decisions and determine if you can modify the design so that you do not have to rely on submitted inputs at all. For example, you may be able to keep critical information about the user's session on the server side instead of recording it within external data.

Relationships

Relevant to the view "Research Concepts" (View-1000)

Nature	Type	ID	Name
ChildOf	Pillar - a weakness that is the most abstract type of weakness and represents a theme for all class/base/variant weaknesses related to it. A Pillar is different from a Category as a Pillar is still technically a type of weakness that describes a mistake, while a Category represents a common characteristic used to group related things.	693	Protection Mechanism Failure
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	302	Authentication Bypass by Assumed-Immutable Data
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	350	Reliance on Reverse DNS Resolution for a Security-Critical Action
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	784	Reliance on Cookies without Validation and Integrity Checking in a Security Decision

Relevant to the view "Software Development" (View-699)

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1006	Bad Coding Practices

Relevant to the view "Architectural Concepts" (View-1008)

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1012	Cross Cutting

Modes Of Introduction

Phase	Note
Architecture and Design	COMMISSION: This weakness refers to an incorrect design related to an architectural security tactic.
Implementation

Applicable Platforms

Languages

Class: Not Language-Specific (Undetermined Prevalence)

Likelihood Of Exploit

High

Demonstrative Examples

Example 1

The following code excerpt reads a value from a browser cookie to determine the role of the user.

(bad code)

Example Language: Java

Cookie[] cookies = request.getCookies();
for (int i =0; i< cookies.length; i++) {

Cookie c = cookies[i];
if (c.getName().equals("role")) {

userRole = c.getValue();

}

Example 2

The following code could be for a medical records application. It performs authentication by checking if a cookie has been set.

(bad code)

Example Language: PHP

$auth = $_COOKIES['authenticated'];
if (! $auth) {

if (AuthenticateUser($_POST['user'], $_POST['password']) == "success") {

// save the cookie to send out in future responses
setcookie("authenticated", "1", time()+60*60*2);

}
else {

ShowLoginScreen();
die("\n");

}

}
DisplayMedicalHistory($_POST['patient_ID']);

The programmer expects that the AuthenticateUser() check will always be applied, and the "authenticated" cookie will only be set when authentication succeeds. The programmer even diligently specifies a 2-hour expiration for the cookie.

However, the attacker can set the "authenticated" cookie to a non-zero value such as 1. As a result, the $auth variable is 1, and the AuthenticateUser() check is not even performed. The attacker has bypassed the authentication.

Example 3

In the following example, an authentication flag is read from a browser cookie, thus allowing for external control of user state data.

(bad code)

Example Language: Java

Cookie[] cookies = request.getCookies();
for (int i =0; i< cookies.length; i++) {

Cookie c = cookies[i];
if (c.getName().equals("authenticated") && Boolean.TRUE.equals(c.getValue())) {

authenticated = true;

}

Example 4

The following code samples use a DNS lookup in order to decide whether or not an inbound request is from a trusted host. If an attacker can poison the DNS cache, they can gain trusted status.

(bad code)

Example Language: C

struct hostent *hp;struct in_addr myaddr;
char* tHost = "trustme.example.com";
myaddr.s_addr=inet_addr(ip_addr_string);

hp = gethostbyaddr((char *) &myaddr, sizeof(struct in_addr), AF_INET);
if (hp && !strncmp(hp->h_name, tHost, sizeof(tHost))) {

trusted = true;

} else {

trusted = false;

}

(bad code)

Example Language: Java

String ip = request.getRemoteAddr();
InetAddress addr = InetAddress.getByName(ip);
if (addr.getCanonicalHostName().endsWith("trustme.com")) {

trusted = true;

}

(bad code)

Example Language: C#

IPAddress hostIPAddress = IPAddress.Parse(RemoteIpAddress);
IPHostEntry hostInfo = Dns.GetHostByAddress(hostIPAddress);
if (hostInfo.HostName.EndsWith("trustme.com")) {

trusted = true;

}

IP addresses are more reliable than DNS names, but they can also be spoofed. Attackers can easily forge the source IP address of the packets they send, but response packets will return to the forged IP address. To see the response packets, the attacker has to sniff the traffic between the victim machine and the forged IP address. In order to accomplish the required sniffing, attackers typically attempt to locate themselves on the same subnet as the victim machine. Attackers may be able to circumvent this requirement by using source routing, but source routing is disabled across much of the Internet today. In summary, IP address verification can be a useful part of an authentication scheme, but it should not be the single factor required for authentication.

Selected Observed Examples

Reference	Description
CVE-2009-1549	Attacker can bypass authentication by setting a cookie to a specific value.
CVE-2009-1619	Attacker can bypass authentication and gain admin privileges by setting an "admin" cookie to 1.
CVE-2009-0864	Content management system allows admin privileges by setting a "login" cookie to "OK."
CVE-2008-5784	e-dating application allows admin privileges by setting the admin cookie to 1.
CVE-2008-6291	Web-based email list manager allows attackers to gain admin privileges by setting a login cookie to "admin."

Detection Methods

Method	Details
Manual Static Analysis	Since this weakness does not typically appear frequently within a single software package, manual white box techniques may be able to provide sufficient code coverage and reduction of false positives if all potentially-vulnerable operations can be assessed within limited time constraints. Effectiveness: High Note:The effectiveness and speed of manual analysis will be reduced if the there is not a centralized security mechanism, and the security logic is widely distributed throughout the software.
Automated Static Analysis - Binary or Bytecode	According to SOAR, the following detection techniques may be useful: Cost effective for partial coverage: Bytecode Weakness Analysis - including disassembler + source code weakness analysis Binary Weakness Analysis - including disassembler + source code weakness analysis Effectiveness: SOAR Partial
Manual Static Analysis - Binary or Bytecode	According to SOAR, the following detection techniques may be useful: Cost effective for partial coverage: Binary / Bytecode disassembler - then use manual analysis for vulnerabilities & anomalies Effectiveness: SOAR Partial
Dynamic Analysis with Automated Results Interpretation	According to SOAR, the following detection techniques may be useful: Cost effective for partial coverage: Web Application Scanner Web Services Scanner Database Scanners Effectiveness: SOAR Partial
Dynamic Analysis with Manual Results Interpretation	According to SOAR, the following detection techniques may be useful: Cost effective for partial coverage: Fuzz Tester Framework-based Fuzzer Monitored Virtual Environment - run potentially malicious code in sandbox / wrapper / virtual machine, see if it does anything suspicious Effectiveness: SOAR Partial
Manual Static Analysis - Source Code	According to SOAR, the following detection techniques may be useful: Highly cost effective: Manual Source Code Review (not inspections) Effectiveness: High
Automated Static Analysis - Source Code	According to SOAR, the following detection techniques may be useful: Cost effective for partial coverage: Source code Weakness Analyzer Context-configured Source Code Weakness Analyzer Effectiveness: SOAR Partial
Architecture or Design Review	According to SOAR, the following detection techniques may be useful: Highly cost effective: Inspection (IEEE 1028 standard) (can apply to requirements, design, source code, etc.) Formal Methods / Correct-By-Construction Cost effective for partial coverage: Attack Modeling Effectiveness: High

Memberships

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	803	2010 Top 25 - Porous Defenses
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	859	The CERT Oracle Secure Coding Standard for Java (2011) Chapter 16 - Platform Security (SEC)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	866	2011 Top 25 - Porous Defenses
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	878	CERT C++ Secure Coding Section 10 - Environment (ENV)
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	884	CWE Cross-section
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1348	OWASP Top Ten 2021 Category A04:2021 - Insecure Design
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1365	ICS Communications: Unreliability
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1373	ICS Engineering (Construction/Deployment): Trust Model Problems
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1413	Comprehensive Categorization: Protection Mechanism Failure

Vulnerability Mapping Notes

Usage	ALLOWED (this CWE ID may be used to map to real-world vulnerabilities)
Reason	Acceptable-Use
Rationale	This CWE entry is at the Base level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.
Comments	Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction.

Taxonomy Mappings

Mapped Taxonomy Name	Node ID	Fit	Mapped Node Name
The CERT Oracle Secure Coding Standard for Java (2011)	SEC09-J		Do not base security checks on untrusted sources

References

[REF-754]	Frank Kim. "Top 25 Series - Rank 6 - Reliance on Untrusted Inputs in a Security Decision". SANS Software Security Institute. 2010-03-05. <https://www.sans.org/blog/top-25-series-rank-6-reliance-on-untrusted-inputs-in-a-security-decision/>. (URL validated: 2023-04-07)
[REF-529]	"HMAC". Wikipedia. 2011-08-18. <https://en.wikipedia.org/wiki/HMAC>. (URL validated: 2023-04-07)
[REF-756]	Scott Mitchell. "Understanding ASP.NET View State". Microsoft. 2004-05-15. <https://learn.microsoft.com/en-us/previous-versions/dotnet/articles/ms972976(v=msdn.10)?redirectedfrom=MSDN>. (URL validated: 2023-04-07)
[REF-45]	OWASP. "OWASP Enterprise Security API (ESAPI) Project". <http://www.owasp.org/index.php/ESAPI>.

Content History

Submissions
Submission Date	Submitter	Organization
2010-01-18 (CWE 1.8, 2010-02-16)	CWE Content Team	MITRE
2010-01-18 (CWE 1.8, 2010-02-16)
Modifications
Modification Date	Modifier	Organization
2023-06-29	CWE Content Team	MITRE
2023-06-29	updated Mapping_Notes, Relationships
2023-04-27	CWE Content Team	MITRE
2023-04-27	updated Potential_Mitigations, References, Relationships
2023-01-31	CWE Content Team	MITRE
2023-01-31	updated Description
2022-04-28	CWE Content Team	MITRE
2022-04-28	updated Relationships
2021-10-28	CWE Content Team	MITRE
2021-10-28	updated Relationships
2020-02-24	CWE Content Team	MITRE
2020-02-24	updated Relationships
2019-01-03	CWE Content Team	MITRE
2019-01-03	updated Taxonomy_Mappings
2017-11-08	CWE Content Team	MITRE
2017-11-08	updated Likelihood_of_Exploit, Modes_of_Introduction, References, Relationships, Taxonomy_Mappings
2017-01-19	CWE Content Team	MITRE
2017-01-19	updated Related_Attack_Patterns
2014-07-30	CWE Content Team	MITRE
2014-07-30	updated Detection_Factors
2014-02-18	CWE Content Team	MITRE
2014-02-18	updated Potential_Mitigations
2013-07-17	CWE Content Team	MITRE
2013-07-17	updated Relationships
2012-10-30	CWE Content Team	MITRE
2012-10-30	updated Potential_Mitigations
2012-05-11	CWE Content Team	MITRE
2012-05-11	updated Demonstrative_Examples, References, Relationships
2011-09-13	CWE Content Team	MITRE
2011-09-13	updated Potential_Mitigations, References, Relationships, Taxonomy_Mappings
2011-06-27	CWE Content Team	MITRE
2011-06-27	updated Common_Consequences, Relationships
2011-06-01	CWE Content Team	MITRE
2011-06-01	updated Common_Consequences
2010-09-27	CWE Content Team	MITRE
2010-09-27	updated Potential_Mitigations
2010-06-21	CWE Content Team	MITRE
2010-06-21	updated Common_Consequences, Potential_Mitigations, References

Weakness ID: 226

View customized information:

Description

Extended Description

When resources are released, they can be made available for reuse. For example, after memory is de-allocated, an operating system may make the memory available to another process, or disk space may be reallocated when a file is deleted. As removing information requires time and additional resources, operating systems do not usually clear the previously written information.

Even when the resource is reused by the same process, this weakness can arise when new data is not as large as the old data, which leaves portions of the old data still available. Equivalent errors can occur in other situations where the length of data is variable but the associated data structure is not. If memory is not cleared after use, the information may be read by less trustworthy parties when the memory is reallocated.

This weakness can apply in hardware, such as when a device or system switches between power, sleep, or debug states during normal operation, or when execution changes to different users or privilege levels.

Common Consequences

Impact	Details
Read Application Data	Scope: Confidentiality

Potential Mitigations

Phase(s)

Mitigation

Architecture and Design; Implementation

During critical state transitions, information not needed in the next state should be removed or overwritten with fixed patterns (such as all 0's) or random data, before the transition to the next state.

Effectiveness: High

Architecture and Design; Implementation

When releasing, de-allocating, or deleting a resource, overwrite its data and relevant metadata with fixed patterns or random data. Be cautious about complex resource types whose underlying representation might be non-contiguous or change at a low level, such as how a file might be split into different chunks on a file system, even though "logical" file positions are contiguous at the application layer. Such resource types might require invocation of special modes or APIs to tell the underlying operating system to perform the necessary clearing, such as SDelete (Secure Delete) on Windows, although the appropriate functionality might not be available at the application layer.

Effectiveness: High

Relationships

Relevant to the view "Research Concepts" (View-1000)

Nature	Type	ID	Name
ChildOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	212	Improper Removal of Sensitive Information Before Storage or Transfer
ChildOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	459	Incomplete Cleanup
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	244	Improper Clearing of Heap Memory Before Release ('Heap Inspection')
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	1239	Improper Zeroization of Hardware Register
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	1272	Sensitive Information Uncleared Before Debug/Power State Transition
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	1301	Insufficient or Incomplete Data Removal within Hardware Component
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	1342	Information Exposure through Microarchitectural State after Transient Execution
CanPrecede	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	201	Insertion of Sensitive Information Into Sent Data

Relevant to the view "Hardware Design" (View-1194)

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1202	Memory and Storage Issues
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	1239	Improper Zeroization of Hardware Register
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	1342	Information Exposure through Microarchitectural State after Transient Execution

Modes Of Introduction

Phase	Note
Implementation

Applicable Platforms

Languages	Class: Not Language-Specific (Undetermined Prevalence)
Technologies	Class: Not Technology-Specific (Undetermined Prevalence)

Demonstrative Examples

Example 1

This example shows how an attacker can take advantage of an incorrect state transition.

Suppose a device is transitioning from state A to state B. During state A, it can read certain private keys from the hidden fuses that are only accessible in state A but not in state B. The device reads the keys, performs operations using those keys, then transitions to state B, where those private keys should no longer be accessible.

(bad code)

Example Language: Other

During the transition from A to B, the device does not scrub the memory.

After the transition to state B, even though the private keys are no longer accessible directly from the fuses in state B, they can be accessed indirectly by reading the memory that contains the private keys.

(good code)

Example Language: Other

For transition from state A to state B, remove information which should not be available once the transition is complete.

Example 2

The following code calls realloc() on a buffer containing sensitive data:

(bad code)

Example Language: C

cleartext_buffer = get_secret();...
cleartext_buffer = realloc(cleartext_buffer, 1024);
...
scrub_memory(cleartext_buffer, 1024);

There is an attempt to scrub the sensitive data from memory, but realloc() is used, so it could return a pointer to a different part of memory. The memory that was originally allocated for cleartext_buffer could still contain an uncleared copy of the data.

Example 3

The following example code is excerpted from the AES wrapper/interface, aes0_wrapper, module of one of the AES engines (AES0) in the Hack@DAC'21 buggy OpenPiton System-on-Chip (SoC). Note that this SoC contains three distinct AES engines. Within this wrapper module, four 32-bit registers are utilized to store the message intended for encryption, referred to as p_c[i]. Using the AXI Lite interface, these registers are filled with the 128-bit message to be encrypted.

(bad code)

Example Language: Verilog

module aes0_wrapper #(...)(...);
...
always @(posedge clk_i)

begin

if(~(rst_ni && ~rst_1)) //clear p_c[i] at reset

begin

start <= 0;
p_c[0] <= 0;
p_c[1] <= 0;
p_c[2] <= 0;
p_c[3] <= 0;
...

end

else if(en && we)

case(address[8:3])

start <= reglk_ctrl_i[1] ? start : wdata[0];

p_c[3] <= reglk_ctrl_i[3] ? p_c[3] : wdata[31:0];

p_c[2] <= reglk_ctrl_i[3] ? p_c[2] : wdata[31:0];

p_c[1] <= reglk_ctrl_i[3] ? p_c[1] : wdata[31:0];

p_c[0] <= reglk_ctrl_i[3] ? p_c[0] : wdata[31:0];

...

endcase

end // always @ (posedge wb_clk_i)

endmodule

The above code snippet [REF-1402] illustrates an instance of a vulnerable implementation of the AES wrapper module, where p_c[i] registers are cleared at reset. Otherwise, p_c[i]registers either maintain their old values (if reglk_ctrl_i[3]is true) or get filled through the AXI signal wdata. Note that p_c[i]registers can be read through the AXI Lite interface (not shown in snippet). However, p_c[i] registers are never cleared after their usage once the AES engine has completed the encryption process of the message. In a multi-user or multi-process environment, not clearing registers may result in the attacker process accessing data left by the victim, leading to data leakage or unintentional information disclosure.

To fix this issue, it is essential to ensure that these internal registers are cleared in a timely manner after their usage, i.e., the encryption process is complete. This is illustrated below by monitoring the assertion of the cipher text valid signal, ct_valid [REF-1403].

(good code)

Example Language: Verilog

module aes0_wrapper #(...)(...);
...
always @(posedge clk_i)

begin

if(~(rst_ni && ~rst_1)) //clear p_c[i] at reset

...

else if(ct_valid) //encryption process complete, clear p_c[i]

begin

p_c[0] <= 0;
p_c[1] <= 0;
p_c[2] <= 0;
p_c[3] <= 0;

end

else if(en && we)

case(address[8:3])
...
endcase

end // always @ (posedge wb_clk_i)

endmodule

Selected Observed Examples

Reference	Description
CVE-2019-3733	Cryptography library does not clear heap memory before release
CVE-2003-0001	Ethernet NIC drivers do not pad frames with null bytes, leading to infoleak from malformed packets.
CVE-2003-0291	router does not clear information from DHCP packets that have been previously used
CVE-2005-1406	Products do not fully clear memory buffers when less data is stored into the buffer than previous.
CVE-2005-1858	Products do not fully clear memory buffers when less data is stored into the buffer than previous.
CVE-2005-3180	Products do not fully clear memory buffers when less data is stored into the buffer than previous.
CVE-2005-3276	Product does not clear a data structure before writing to part of it, yielding information leak of previously used memory.
CVE-2002-2077	Memory not properly cleared before reuse.

Weakness Ordinalities

Ordinality	Description
Primary	(where the weakness exists independent of other weaknesses)

Detection Methods

Method

Details

Manual Analysis

Write a known pattern into each sensitive location. Trigger the release of the resource or cause the desired state transition to occur. Read data back from the sensitive locations. If the reads are successful, and the data is the same as the pattern that was originally written, the test fails and the product needs to be fixed. Note that this test can likely be automated.

Effectiveness: High

Automated Static Analysis

Effectiveness: High

Functional Areas

Memory Management
Networking

Affected Resources

Memory

Memberships

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	729	OWASP Top Ten 2004 Category A8 - Insecure Storage
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	742	CERT C Secure Coding Standard (2008) Chapter 9 - Memory Management (MEM)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	876	CERT C++ Secure Coding Section 08 - Memory Management (MEM)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	963	SFP Secondary Cluster: Exposed Data
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1416	Comprehensive Categorization: Resource Lifecycle Management

Vulnerability Mapping Notes

Usage	ALLOWED (this CWE ID may be used to map to real-world vulnerabilities)
Reason	Acceptable-Use
Rationale	This CWE entry is at the Base level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.
Comments	Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction.

Notes

Relationship

There is a close association between CWE-226 and CWE-212. The difference is partially that of perspective. CWE-226 is geared towards the final stage of the resource lifecycle, in which the resource is deleted, eliminated, expired, or otherwise released for reuse. Technically, this involves a transfer to a different control sphere, in which the original contents of the resource are no longer relevant. CWE-212, however, is intended for sensitive data in resources that are intentionally shared with others, so they are still active. This distinction is useful from the perspective of the CWE research view (CWE-1000).

Research Gap

This is frequently found for network packets, but it can also exist in local memory allocation, files, etc.

Maintenance

This entry needs modification to clarify the differences with CWE-212. The description also combines two problems that are distinct from the CWE research perspective: the inadvertent transfer of information to another sphere, and improper initialization/shutdown. Some of the associated taxonomy mappings reflect these different uses.

Taxonomy Mappings

Mapped Taxonomy Name	Node ID	Mapped Node Name
PLOVER		Sensitive Information Uncleared Before Use
CERT C Secure Coding	MEM03-C	Clear sensitive information stored in reusable resources returned for reuse
Software Fault Patterns	SFP23	Exposed Data

Related Attack Patterns

CAPEC-ID	Attack Pattern Name
CAPEC-37	Retrieve Embedded Sensitive Data

References

[REF-1402]	"aes0_wrapper.sv". 2021. <https://github.com/HACK-EVENT/hackatdac21/blob/65d0ffdab7426da4509c98d62e163bcce642f651/piton/design/chip/tile/ariane/src/aes0/aes0_wrapper.sv#L84C2-L90C29>. (URL validated: 2024-02-14)
[REF-1403]	"Fix for aes0_wrapper". 2023-11-29. <https://github.com/HACK-EVENT/hackatdac21/blob/0034dff6852365a8c4e36590a47ea8b088d725ae/piton/design/chip/tile/ariane/src/aes0/aes0_wrapper.sv#L96C1-L102C16>. (URL validated: 2024-02-14)

Content History

Submissions
Submission Date	Submitter	Organization
2006-07-19 (CWE Draft 3, 2006-07-19)	PLOVER
2006-07-19 (CWE Draft 3, 2006-07-19)
Contributions
Contribution Date	Contributor	Organization
2023-11-29 (CWE 4.14, 2024-02-29)	Rahul Kande, Chen Chen, Jeyavijayan Rajendran	Texas A&M University
2023-11-29 (CWE 4.14, 2024-02-29)	suggested demonstrative example
2023-11-29 (CWE 4.14, 2024-02-29)	Mohamadreza Rostami, Shaza Zeitouni, Ahmad-Reza Sadeghi	Technical University of Darmstadt
2023-11-29 (CWE 4.14, 2024-02-29)	suggested demonstrative example
Modifications
Modification Date	Modifier	Organization
2025-04-03 (CWE 4.17, 2025-04-03)	CWE Content Team	MITRE
2025-04-03 (CWE 4.17, 2025-04-03)	updated Demonstrative_Examples
2024-02-29 (CWE 4.14, 2024-02-29)	CWE Content Team	MITRE
2024-02-29 (CWE 4.14, 2024-02-29)	updated Demonstrative_Examples, Observed_Examples, References
2023-06-29	CWE Content Team	MITRE
2023-06-29	updated Mapping_Notes
2023-04-27	CWE Content Team	MITRE
2023-04-27	updated Detection_Factors, Relationships, Time_of_Introduction
2021-10-28	CWE Content Team	MITRE
2021-10-28	updated Demonstrative_Examples, Description, Detection_Factors, Maintenance_Notes, Potential_Mitigations, Relationships, Research_Gaps
2020-08-20	CWE Content Team	MITRE
2020-08-20	updated Description, Name, Related_Attack_Patterns, Relationships
2020-02-24	CWE Content Team	MITRE
2020-02-24	updated Applicable_Platforms, Description, Name, Relationships, Time_of_Introduction, Weakness_Ordinalities
2017-11-08	CWE Content Team	MITRE
2017-11-08	updated Causal_Nature, Functional_Areas, Relationships, Taxonomy_Mappings
2014-07-30	CWE Content Team	MITRE
2014-07-30	updated Relationships, Taxonomy_Mappings
2012-05-11	CWE Content Team	MITRE
2012-05-11	updated Relationships, Taxonomy_Mappings
2011-09-13	CWE Content Team	MITRE
2011-09-13	updated Relationships, Taxonomy_Mappings
2011-06-01	CWE Content Team	MITRE
2011-06-01	updated Common_Consequences, Relationships, Taxonomy_Mappings
2010-12-13	CWE Content Team	MITRE
2010-12-13	updated Description
2010-09-27	CWE Content Team	MITRE
2010-09-27	updated Relationships
2010-02-16	CWE Content Team	MITRE
2010-02-16	updated Applicable_Platforms, Maintenance_Notes, Relationship_Notes
2009-10-29	CWE Content Team	MITRE
2009-10-29	updated Description, Other_Notes
2009-05-27	CWE Content Team	MITRE
2009-05-27	updated Relationships
2009-03-10	CWE Content Team	MITRE
2009-03-10	updated Relationships
2008-11-24	CWE Content Team	MITRE
2008-11-24	updated Relationships, Taxonomy_Mappings
2008-10-14	CWE Content Team	MITRE
2008-10-14	updated Relationships
2008-09-08	CWE Content Team	MITRE
2008-09-08	updated Relationships, Other_Notes, Relationship_Notes, Taxonomy_Mappings, Weakness_Ordinalities
2008-07-01	Eric Dalci	Cigital
2008-07-01	updated Time_of_Introduction
Previous Entry Names
Change Date	Previous Entry Name
2008-04-11	Sensitive Information Uncleared Before Use
2020-02-24	Sensitive Information Uncleared Before Release
2020-08-20	Sensitive Information Uncleared in Resource Before Release for Reuse

Weakness ID: 367

View customized information:

Description

Extended Description

This weakness can be security-relevant when an attacker can influence the state of the resource between check and use. This can happen with shared resources such as files, memory, or even variables in multithreaded programs.

Alternate Terms

TOCTTOU	The TOCTTOU acronym expands to "Time Of Check To Time Of Use".
TOCCTOU	The TOCCTOU acronym is most likely a typo of TOCTTOU, but it has been used in some influential documents, so the typo is repeated fairly frequently.

Common Consequences

Impact	Details
Alter Execution Logic; Unexpected State	Scope: Integrity, Other The attacker can gain access to otherwise unauthorized resources.
Modify Application Data; Modify Files or Directories; Modify Memory; Other	Scope: Integrity, Other Race conditions such as this kind may be employed to gain read or write access to resources which are not normally readable or writable by the user in question.
Other	Scope: Integrity, Other The resource in question, or other resources (through the corrupted one), may be changed in undesirable ways by a malicious user.
Hide Activities	Scope: Non-Repudiation If a file or other resource is written in this method, as opposed to in a valid way, logging of the activity may not occur.
Other	Scope: Non-Repudiation, Other In some cases it may be possible to delete files a malicious user might not otherwise have access to, such as log files.

Potential Mitigations

Phase(s)	Mitigation
Implementation	The most basic advice for TOCTOU vulnerabilities is to not perform a check before the use. This does not resolve the underlying issue of the execution of a function on a resource whose state and identity cannot be assured, but it does help to limit the false sense of security given by the check.
Implementation	When the file being altered is owned by the current user and group, set the effective gid and uid to that of the current user and group when executing this statement.
Architecture and Design	Limit the interleaving of operations on files from multiple processes.
Implementation; Architecture and Design	If you cannot perform operations atomically and you must share access to the resource between multiple processes or threads, then try to limit the amount of time (CPU cycles) between the check and use of the resource. This will not fix the problem, but it could make it more difficult for an attack to succeed.
Implementation	Recheck the resource after the use call to verify that the action was taken appropriately.
Architecture and Design	Ensure that some environmental locking mechanism can be used to protect resources effectively.
Implementation	Ensure that locking occurs before the check, as opposed to afterwards, such that the resource, as checked, is the same as it is when in use.

Relationships

Relevant to the view "Research Concepts" (View-1000)

Nature	Type	ID	Name
ChildOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	362	Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	363	Race Condition Enabling Link Following
PeerOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	386	Symbolic Name not Mapping to Correct Object
CanFollow	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	609	Double-Checked Locking

Relevant to the view "Software Development" (View-699)

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	557	Concurrency Issues

Relevant to the view "Weaknesses for Simplified Mapping of Published Vulnerabilities" (View-1003)

Nature	Type	ID	Name
ChildOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	362	Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

Modes Of Introduction

Phase	Note
Implementation

Applicable Platforms

Languages

Class: Not Language-Specific (Undetermined Prevalence)

Likelihood Of Exploit

Medium

Demonstrative Examples

Example 1

The following code checks a file, then updates its contents.

(bad code)

Example Language: C

struct stat *sb;
...
lstat("...",sb); // it has not been updated since the last time it was read
printf("stated file\n");
if (sb->st_mtimespec==...){

print("Now updating things\n");
updateThings();

}

Potentially the file could have been updated between the time of the check and the lstat, especially since the printf has latency.

Example 2

The following code is from a program installed setuid root. The program performs certain file operations on behalf of non-privileged users, and uses access checks to ensure that it does not use its root privileges to perform operations that should otherwise be unavailable the current user. The program uses the access() system call to check if the person running the program has permission to access the specified file before it opens the file and performs the necessary operations.

(bad code)

Example Language: C

if(!access(file,W_OK)) {

f = fopen(file,"w+");
operate(f);
...

}
else {

fprintf(stderr,"Unable to open file %s.\n",file);

}

The call to access() behaves as expected, and returns 0 if the user running the program has the necessary permissions to write to the file, and -1 otherwise. However, because both access() and fopen() operate on filenames rather than on file handles, there is no guarantee that the file variable still refers to the same file on disk when it is passed to fopen() that it did when it was passed to access(). If an attacker replaces file after the call to access() with a symbolic link to a different file, the program will use its root privileges to operate on the file even if it is a file that the attacker would otherwise be unable to modify. By tricking the program into performing an operation that would otherwise be impermissible, the attacker has gained elevated privileges. This type of vulnerability is not limited to programs with root privileges. If the application is capable of performing any operation that the attacker would not otherwise be allowed perform, then it is a possible target.

Example 3

This code prints the contents of a file if a user has permission.

(bad code)

Example Language: PHP

function readFile($filename){

$user = getCurrentUser();

//resolve file if its a symbolic link
if(is_link($filename)){

$filename = readlink($filename);

}

if(fileowner($filename) == $user){

echo file_get_contents($realFile);
return;

}
else{

echo 'Access denied';
return false;

}

This code attempts to resolve symbolic links before checking the file and printing its contents. However, an attacker may be able to change the file from a real file to a symbolic link between the calls to is_link() and file_get_contents(), allowing the reading of arbitrary files. Note that this code fails to log the attempted access (CWE-778).

Example 4

This example is adapted from [REF-18]. Assume that this code block is invoked from multiple threads. The switch statement will execute different code depending on the time when MYFILE.txt was last changed.

(bad code)

Example Language: C

#include <sys/types.h>
#include <sys/stat.h>

...

struct stat sb;
stat("MYFILE.txt",&sb);
printf("file change time: %d\n",sb->st_ctime);
switch(sb->st_ctime % 2){

case 0: printf("Option 1\n"); break;
case 1: printf("Option 2\n"); break;
default: printf("this should be unreachable?\n"); break;

}

If this code block were executed within multiple threads, and MYFILE.txt changed between the operation of one thread and another, then the switch could produce different, possibly unexpected results.

Selected Observed Examples

Reference	Description
CVE-2015-1743	TOCTOU in sandbox process allows installation of untrusted browser add-ons by replacing a file after it has been verified, but before it is executed
CVE-2003-0813	Chain: A multi-threaded race condition (CWE-367) allows attackers to cause two threads to process the same RPC request, which causes a use-after-free (CWE-416) in one thread
CVE-2004-0594	PHP flaw allows remote attackers to execute arbitrary code by aborting execution before the initialization of key data structures is complete.
CVE-2008-2958	chain: time-of-check time-of-use (TOCTOU) race condition in program allows bypass of protection mechanism that was designed to prevent symlink attacks.
CVE-2008-1570	chain: time-of-check time-of-use (TOCTOU) race condition in program allows bypass of protection mechanism that was designed to prevent symlink attacks.

Detection Methods

Method

Details

Automated Static Analysis

Effectiveness: High

Affected Resources

File or Directory

Memberships

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	361	7PK - Time and State
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	743	CERT C Secure Coding Standard (2008) Chapter 10 - Input Output (FIO)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	877	CERT C++ Secure Coding Section 09 - Input Output (FIO)
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	884	CWE Cross-section
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	988	SFP Secondary Cluster: Race Condition Window
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1401	Comprehensive Categorization: Concurrency

Vulnerability Mapping Notes

Usage	ALLOWED (this CWE ID may be used to map to real-world vulnerabilities)
Reason	Acceptable-Use
Rationale	This CWE entry is at the Base level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.
Comments	Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction.

Notes

Relationship

TOCTOU issues do not always involve symlinks, and not every symlink issue is a TOCTOU problem.

Research Gap

Non-symlink TOCTOU issues are not reported frequently, but they are likely to occur in code that attempts to be secure.

Taxonomy Mappings

Mapped Taxonomy Name	Node ID	Mapped Node Name
PLOVER		Time-of-check Time-of-use race condition
7 Pernicious Kingdoms		File Access Race Conditions: TOCTOU
CLASP		Time of check, time of use race condition
CLASP		Race condition in switch
CERT C Secure Coding	FIO01-C	Be careful using functions that use file names for identification
Software Fault Patterns	SFP20	Race Condition Window

Related Attack Patterns

CAPEC-ID	Attack Pattern Name
CAPEC-27	Leveraging Race Conditions via Symbolic Links
CAPEC-29	Leveraging Time-of-Check and Time-of-Use (TOCTOU) Race Conditions

References

[REF-18]	Secure Software, Inc.. "The CLASP Application Security Process". 5.4.6 Race condition in switch. 2005. <https://cwe.mitre.org/documents/sources/TheCLASPApplicationSecurityProcess.pdf>. (URL validated: 2024-11-17)
[REF-367]	Dan Tsafrir, Tomer Hertz, David Wagner and Dilma Da Silva. "Portably Solving File TOCTTOU Races with Hardness Amplification". 2008-02-28. <https://www.usenix.org/legacy/events/fast08/tech/tsafrir.html>. (URL validated: 2023-04-07)
[REF-44]	Michael Howard, David LeBlanc and John Viega. "24 Deadly Sins of Software Security". "Sin 13: Race Conditions." Page 205. McGraw-Hill. 2010.
[REF-62]	Mark Dowd, John McDonald and Justin Schuh. "The Art of Software Security Assessment". Chapter 9, "TOCTOU", Page 527. 1st Edition. Addison Wesley. 2006.

Content History

Submissions
Submission Date	Submitter	Organization
2006-07-19 (CWE Draft 3, 2006-07-19)	PLOVER
2006-07-19 (CWE Draft 3, 2006-07-19)
Modifications
Modification Date	Modifier	Organization
2025-04-03 (CWE 4.17, 2025-04-03)	CWE Content Team	MITRE
2025-04-03 (CWE 4.17, 2025-04-03)	updated Affected_Resources, Observed_Examples
2023-06-29	CWE Content Team	MITRE
2023-06-29	updated Mapping_Notes
2023-04-27	CWE Content Team	MITRE
2023-04-27	updated Detection_Factors, References, Relationships
2023-01-31	CWE Content Team	MITRE
2023-01-31	updated Description
2022-06-28	CWE Content Team	MITRE
2022-06-28	updated Observed_Examples
2022-04-28	CWE Content Team	MITRE
2022-04-28	updated Demonstrative_Examples, References, Relationships, Taxonomy_Mappings
2020-02-24	CWE Content Team	MITRE
2020-02-24	updated References, Relationships
2019-06-20	CWE Content Team	MITRE
2019-06-20	updated Relationships
2017-11-08	CWE Content Team	MITRE
2017-11-08	updated Applicable_Platforms, Demonstrative_Examples, Likelihood_of_Exploit, References, Relationships, Taxonomy_Mappings, White_Box_Definitions
2014-07-30	CWE Content Team	MITRE
2014-07-30	updated Demonstrative_Examples, Relationships, Taxonomy_Mappings
2012-10-30	CWE Content Team	MITRE
2012-10-30	updated Potential_Mitigations
2012-05-11	CWE Content Team	MITRE
2012-05-11	updated Demonstrative_Examples, Observed_Examples, References, Relationships
2011-09-13	CWE Content Team	MITRE
2011-09-13	updated Relationships, Taxonomy_Mappings
2011-06-27	CWE Content Team	MITRE
2011-06-27	updated Common_Consequences
2011-06-01	CWE Content Team	MITRE
2011-06-01	updated Common_Consequences
2010-12-13	CWE Content Team	MITRE
2010-12-13	updated Alternate_Terms, Relationships
2010-09-27	CWE Content Team	MITRE
2010-09-27	updated Description, Relationships
2009-07-27	CWE Content Team	MITRE
2009-07-27	updated White_Box_Definitions
2009-07-17	KDM Analytics
2009-07-17	Improved the White_Box_Definition
2009-05-27	CWE Content Team	MITRE
2009-05-27	updated Demonstrative_Examples
2009-01-12	CWE Content Team	MITRE
2009-01-12	updated Alternate_Terms, Observed_Examples, Other_Notes, References, Relationship_Notes, Relationships, Research_Gaps
2008-11-24	CWE Content Team	MITRE
2008-11-24	updated Relationships, Taxonomy_Mappings
2008-10-14	CWE Content Team	MITRE
2008-10-14	updated Description, Name, Relationships
2008-09-08	CWE Content Team	MITRE
2008-09-08	updated Common_Consequences, Relationships, Other_Notes, Taxonomy_Mappings
2008-08-01		KDM Analytics
2008-08-01	added/updated white box definitions
2008-07-01	Eric Dalci	Cigital
2008-07-01	updated Time_of_Introduction
Previous Entry Names
Change Date	Previous Entry Name
2008-10-14	Time-of-check Time-of-use Race Condition

Weakness ID: 252

View customized information:

Description

The product does not check the return value from a method or function, which can prevent it from detecting unexpected states and conditions.

Extended Description

Two common programmer assumptions are "this function call can never fail" and "it doesn't matter if this function call fails". If an attacker can force the function to fail or otherwise return a value that is not expected, then the subsequent program logic could lead to a vulnerability, because the product is not in a state that the programmer assumes. For example, if the program calls a function to drop privileges but does not check the return code to ensure that privileges were successfully dropped, then the program will continue to operate with the higher privileges.

Common Consequences

Impact	Details
Unexpected State; DoS: Crash, Exit, or Restart	Scope: Availability, Integrity An unexpected return value could place the system in a state that could lead to a crash or other unintended behaviors.

Potential Mitigations

Phase(s)	Mitigation
Implementation	Check the results of all functions that return a value and verify that the value is expected. Effectiveness: High Note: Checking the return value of the function will typically be sufficient, however beware of race conditions (CWE-362) in a concurrent environment.
Implementation	Ensure that you account for all possible return values from the function.
Implementation	When designing a function, make sure you return a value or throw an exception in case of an error.

Relationships

Relevant to the view "Research Concepts" (View-1000)

Nature	Type	ID	Name
ChildOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	754	Improper Check for Unusual or Exceptional Conditions
ParentOf	Chain - a Compound Element that is a sequence of two or more separate weaknesses that can be closely linked together within software. One weakness, X, can directly create the conditions that are necessary to cause another weakness, Y, to enter a vulnerable condition. When this happens, CWE refers to X as "primary" to Y, and Y is "resultant" from X. Chains can involve more than two weaknesses, and in some cases, they might have a tree-like structure.	690	Unchecked Return Value to NULL Pointer Dereference
PeerOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	273	Improper Check for Dropped Privileges
CanPrecede	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	476	NULL Pointer Dereference

Relevant to the view "Software Development" (View-699)

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	389	Error Conditions, Return Values, Status Codes

Relevant to the view "Weaknesses for Simplified Mapping of Published Vulnerabilities" (View-1003)

Nature	Type	ID	Name
ChildOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	754	Improper Check for Unusual or Exceptional Conditions

Background Details

Many functions will return some value about the success of their actions. This will alert the program whether or not to handle any errors caused by that function.

Modes Of Introduction

Phase	Note
Implementation

Applicable Platforms

Languages

Class: Not Language-Specific (Undetermined Prevalence)

Likelihood Of Exploit

Low

Demonstrative Examples

Example 1

Consider the following code segment:

(bad code)

Example Language: C

char buf[10], cp_buf[10];
fgets(buf, 10, stdin);
strcpy(cp_buf, buf);

Example 2

In the following example, it is possible to request that memcpy move a much larger segment of memory than assumed:

(bad code)

Example Language: C

int returnChunkSize(void *) {

/* if chunk info is valid, return the size of usable memory,

* else, return -1 to indicate an error

*/
...

}
int main() {

...
memcpy(destBuf, srcBuf, (returnChunkSize(destBuf)-1));
...

}

Example 3

The following code does not check to see if memory allocation succeeded before attempting to use the pointer returned by malloc().

(bad code)

Example Language: C

buf = (char*) malloc(req_size);
strncpy(buf, xfer, req_size);

The traditional defense of this coding error is: "If my program runs out of memory, it will fail. It doesn't matter whether I handle the error or allow the program to die with a segmentation fault when it tries to dereference the null pointer." This argument ignores three important considerations:

Depending upon the type and size of the application, it may be possible to free memory that is being used elsewhere so that execution can continue.
It is impossible for the program to perform a graceful exit if required. If the program is performing an atomic operation, it can leave the system in an inconsistent state.
The programmer has lost the opportunity to record diagnostic information. Did the call to malloc() fail because req_size was too large or because there were too many requests being handled at the same time? Or was it caused by a memory leak that has built up over time? Without handling the error, there is no way to know.

Example 4

The following examples read a file into a byte array.

(bad code)

Example Language: C#

char[] byteArray = new char[1024];
for (IEnumerator i=users.GetEnumerator(); i.MoveNext() ;i.Current()) {

}

(bad code)

Example Language: Java

FileInputStream fis;
byte[] byteArray = new byte[1024];
for (Iterator i=users.iterator(); i.hasNext();) {

Example 5

The following code does not check to see if the string returned by getParameter() is null before calling the member function compareTo(), potentially causing a NULL dereference.

(bad code)

Example Language: Java

String itemName = request.getParameter(ITEM_NAME);
if (itemName.compareTo(IMPORTANT_ITEM) == 0) {

...

}
...

The following code does not check to see if the string returned by the Item property is null before calling the member function Equals(), potentially causing a NULL dereference.

(bad code)

Example Language: Java

String itemName = request.Item(ITEM_NAME);
if (itemName.Equals(IMPORTANT_ITEM)) {

...

}
...

The traditional defense of this coding error is: "I know the requested value will always exist because.... If it does not exist, the program cannot perform the desired behavior so it doesn't matter whether I handle the error or allow the program to die dereferencing a null value." But attackers are skilled at finding unexpected paths through programs, particularly when exceptions are involved.

Example 6

The following code shows a system property that is set to null and later dereferenced by a programmer who mistakenly assumes it will always be defined.

(bad code)

Example Language: Java

System.clearProperty("os.name");
...
String os = System.getProperty("os.name");
if (os.equalsIgnoreCase("Windows 95")) System.out.println("Not supported");

The traditional defense of this coding error is: "I know the requested value will always exist because.... If it does not exist, the program cannot perform the desired behavior so it doesn't matter whether I handle the error or allow the program to die dereferencing a null value." But attackers are skilled at finding unexpected paths through programs, particularly when exceptions are involved.

Example 7

The following VB.NET code does not check to make sure that it has read 50 bytes from myfile.txt. This can cause DoDangerousOperation() to operate on an unexpected value.

(bad code)

Example Language: C#

Dim MyFile As New FileStream("myfile.txt", FileMode.Open, FileAccess.Read, FileShare.Read)
Dim MyArray(50) As Byte
MyFile.Read(MyArray, 0, 50)
DoDangerousOperation(MyArray(20))

Example 8

It is not uncommon for Java programmers to misunderstand read() and related methods that are part of many java.io classes. Most errors and unusual events in Java result in an exception being thrown. But the stream and reader classes do not consider it unusual or exceptional if only a small amount of data becomes available. These classes simply add the small amount of data to the return buffer, and set the return value to the number of bytes or characters read. There is no guarantee that the amount of data returned is equal to the amount of data requested. This behavior makes it important for programmers to examine the return value from read() and other IO methods to ensure that they receive the amount of data they expect.

Example 9

This example takes an IP address from a user, verifies that it is well formed and then looks up the hostname and copies it into a buffer.

(bad code)

Example Language: C

void host_lookup(char *user_supplied_addr){

}

Note that this code is also vulnerable to a buffer overflow (CWE-119).

Example 10

The following function attempts to acquire a lock in order to perform operations on a shared resource.

(bad code)

Example Language: C

void f(pthread_mutex_t *mutex) {

pthread_mutex_lock(mutex);

/* access shared resource */

pthread_mutex_unlock(mutex);

}

(good code)

Example Language: C

int f(pthread_mutex_t *mutex) {

int result;

result = pthread_mutex_lock(mutex);
if (0 != result)

return result;

/* access shared resource */

return pthread_mutex_unlock(mutex);

}

Selected Observed Examples

Reference	Description
CVE-2020-17533	Chain: unchecked return value (CWE-252) of some functions for policy enforcement leads to authorization bypass (CWE-862)
CVE-2020-6078	Chain: The return value of a function returning a pointer is not checked for success (CWE-252) resulting in the later use of an uninitialized variable (CWE-456) and a null pointer dereference (CWE-476)
CVE-2019-15900	Chain: sscanf() call is used to check if a username and group exists, but the return value of sscanf() call is not checked (CWE-252), causing an uninitialized variable to be checked (CWE-457), returning success to allow authorization bypass for executing a privileged (CWE-863).
CVE-2007-3798	Unchecked return value leads to resultant integer overflow and code execution.
CVE-2006-4447	Program does not check return value when invoking functions to drop privileges, which could leave users with higher privileges than expected by forcing those functions to fail.
CVE-2006-2916	Program does not check return value when invoking functions to drop privileges, which could leave users with higher privileges than expected by forcing those functions to fail.
CVE-2008-5183	chain: unchecked return value can lead to NULL dereference
CVE-2010-0211	chain: unchecked return value (CWE-252) leads to free of invalid, uninitialized pointer (CWE-824).
CVE-2017-6964	Linux-based device mapper encryption program does not check the return value of setuid and setgid allowing attackers to execute code with unintended privileges.
CVE-2002-1372	Chain: Return values of file/socket operations are not checked (CWE-252), allowing resultant consumption of file descriptors (CWE-772).

Weakness Ordinalities

Ordinality	Description
Primary	(where the weakness exists independent of other weaknesses)

Detection Methods

Method

Details

Automated Static Analysis

Effectiveness: High

Memberships

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	227	7PK - API Abuse
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	728	OWASP Top Ten 2004 Category A7 - Improper Error Handling
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	742	CERT C Secure Coding Standard (2008) Chapter 9 - Memory Management (MEM)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	847	The CERT Oracle Secure Coding Standard for Java (2011) Chapter 4 - Expressions (EXP)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	876	CERT C++ Secure Coding Section 08 - Memory Management (MEM)
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	884	CWE Cross-section
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	962	SFP Secondary Cluster: Unchecked Status Condition
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1129	CISQ Quality Measures (2016) - Reliability
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1131	CISQ Quality Measures (2016) - Security
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1136	SEI CERT Oracle Secure Coding Standard for Java - Guidelines 02. Expressions (EXP)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1167	SEI CERT C Coding Standard - Guidelines 12. Error Handling (ERR)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1171	SEI CERT C Coding Standard - Guidelines 50. POSIX (POS)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1181	SEI CERT Perl Coding Standard - Guidelines 03. Expressions (EXP)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1306	CISQ Quality Measures - Reliability
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1308	CISQ Quality Measures - Security
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1405	Comprehensive Categorization: Improper Check or Handling of Exceptional Conditions

Vulnerability Mapping Notes

Usage	ALLOWED (this CWE ID may be used to map to real-world vulnerabilities)
Reason	Acceptable-Use
Rationale	This CWE entry is at the Base level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.
Comments	Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction.

Taxonomy Mappings

Mapped Taxonomy Name	Node ID	Fit	Mapped Node Name
7 Pernicious Kingdoms			Unchecked Return Value
CLASP			Ignored function return value
OWASP Top Ten 2004	A7	CWE More Specific	Improper Error Handling
CERT C Secure Coding	ERR33-C	Imprecise	Detect and handle standard library errors
CERT C Secure Coding	POS54-C	Imprecise	Detect and handle POSIX library errors
The CERT Oracle Secure Coding Standard for Java (2011)	EXP00-J		Do not ignore values returned by methods
SEI CERT Perl Coding Standard	EXP32-PL	Exact	Do not ignore function return values
Software Fault Patterns	SFP4		Unchecked Status Condition
OMG ASCSM	ASCSM-CWE-252-resource
OMG ASCRM	ASCRM-CWE-252-data
OMG ASCRM	ASCRM-CWE-252-resource

References

[REF-6]	Katrina Tsipenyuk, Brian Chess and Gary McGraw. "Seven Pernicious Kingdoms: A Taxonomy of Software Security Errors". NIST Workshop on Software Security Assurance Tools Techniques and Metrics. NIST. 2005-11-07. <https://samate.nist.gov/SSATTM_Content/papers/Seven%20Pernicious%20Kingdoms%20-%20Taxonomy%20of%20Sw%20Security%20Errors%20-%20Tsipenyuk%20-%20Chess%20-%20McGraw.pdf>.
[REF-62]	Mark Dowd, John McDonald and Justin Schuh. "The Art of Software Security Assessment". Chapter 7, "Program Building Blocks" Page 341. 1st Edition. Addison Wesley. 2006.
[REF-7]	Michael Howard and David LeBlanc. "Writing Secure Code". Chapter 20, "Checking Returns" Page 624. 2nd Edition. Microsoft Press. 2002-12-04. <https://www.microsoftpressstore.com/store/writing-secure-code-9780735617223>.
[REF-44]	Michael Howard, David LeBlanc and John Viega. "24 Deadly Sins of Software Security". "Sin 11: Failure to Handle Errors Correctly." Page 183. McGraw-Hill. 2010.
[REF-961]	Object Management Group (OMG). "Automated Source Code Reliability Measure (ASCRM)". ASCRM-CWE-252-data. 2016-01. <http://www.omg.org/spec/ASCRM/1.0/>.
[REF-961]	Object Management Group (OMG). "Automated Source Code Reliability Measure (ASCRM)". ASCRM-CWE-252-resource. 2016-01. <http://www.omg.org/spec/ASCRM/1.0/>.
[REF-962]	Object Management Group (OMG). "Automated Source Code Security Measure (ASCSM)". ASCSM-CWE-252-resource. 2016-01. <http://www.omg.org/spec/ASCSM/1.0/>.

Content History

Submissions
Submission Date	Submitter	Organization
2006-07-19 (CWE Draft 3, 2006-07-19)	7 Pernicious Kingdoms
2006-07-19 (CWE Draft 3, 2006-07-19)
Contributions
Contribution Date	Contributor	Organization
2010-04-30	Martin Sebor	Cisco Systems, Inc.
2010-04-30	Provided Demonstrative Example and suggested CERT reference
Modifications
Modification Date	Modifier	Organization
2023-10-26	CWE Content Team	MITRE
2023-10-26	updated Observed_Examples
2023-06-29	CWE Content Team	MITRE
2023-06-29	updated Mapping_Notes, Relationships
2023-04-27	CWE Content Team	MITRE
2023-04-27	updated Detection_Factors, Relationships
2023-01-31	CWE Content Team	MITRE
2023-01-31	updated Description
2021-07-20	CWE Content Team	MITRE
2021-07-20	updated Observed_Examples
2021-03-15	CWE Content Team	MITRE
2021-03-15	updated Demonstrative_Examples, Observed_Examples, Relationships, Weakness_Ordinalities
2020-08-20	CWE Content Team	MITRE
2020-08-20	updated Relationships
2020-06-25	CWE Content Team	MITRE
2020-06-25	updated Observed_Examples
2020-02-24	CWE Content Team	MITRE
2020-02-24	updated References
2019-06-20	CWE Content Team	MITRE
2019-06-20	updated Relationships
2019-01-03	CWE Content Team	MITRE
2019-01-03	updated References, Relationships, Taxonomy_Mappings
2018-03-27	CWE Content Team	MITRE
2018-03-27	updated References
2017-11-08	CWE Content Team	MITRE
2017-11-08	updated Applicable_Platforms, References, Relationships, Taxonomy_Mappings
2014-07-30	CWE Content Team	MITRE
2014-07-30	updated Demonstrative_Examples, Relationships, Taxonomy_Mappings
2014-06-23	CWE Content Team	MITRE
2014-06-23	updated Demonstrative_Examples, Potential_Mitigations
2012-05-11	CWE Content Team	MITRE
2012-05-11	updated Common_Consequences, References, Relationships
2011-09-13	CWE Content Team	MITRE
2011-09-13	updated Relationships, Taxonomy_Mappings
2011-06-27	CWE Content Team	MITRE
2011-06-27	updated Common_Consequences
2011-06-01	CWE Content Team	MITRE
2011-06-01	updated Common_Consequences, Demonstrative_Examples, Relationships, Taxonomy_Mappings
2010-12-13	CWE Content Team	MITRE
2010-12-13	updated Demonstrative_Examples
2010-09-27	CWE Content Team	MITRE
2010-09-27	updated Observed_Examples
2010-06-21	CWE Content Team	MITRE
2010-06-21	updated Demonstrative_Examples, References
2010-04-05	CWE Content Team	MITRE
2010-04-05	updated Demonstrative_Examples
2010-02-16	CWE Content Team	MITRE
2010-02-16	updated Demonstrative_Examples, Potential_Mitigations, References
2009-12-28	CWE Content Team	MITRE
2009-12-28	updated Common_Consequences, Demonstrative_Examples, References
2009-07-27	CWE Content Team	MITRE
2009-07-27	updated Demonstrative_Examples
2009-05-27	CWE Content Team	MITRE
2009-05-27	updated Demonstrative_Examples
2009-03-10	CWE Content Team	MITRE
2009-03-10	updated Relationships
2009-01-12	CWE Content Team	MITRE
2009-01-12	updated Background_Details, Demonstrative_Examples, Description, Observed_Examples, Other_Notes, Potential_Mitigations
2008-11-24	CWE Content Team	MITRE
2008-11-24	updated Relationships, Taxonomy_Mappings
2008-09-08	CWE Content Team	MITRE
2008-09-08	updated Common_Consequences, Relationships, Other_Notes, Taxonomy_Mappings

Weakness ID: 426

View customized information:

Description

The product searches for critical resources using an externally-supplied search path that can point to resources that are not under the product's direct control.

Extended Description

This might allow attackers to execute their own programs, access unauthorized data files, or modify configuration in unexpected ways. If the product uses a search path to locate critical resources such as programs, then an attacker could modify that search path to point to a malicious program, which the targeted product would then execute. The problem extends to any type of critical resource that the product trusts.

Some of the most common variants of untrusted search path are:

In various UNIX and Linux-based systems, the PATH environment variable may be consulted to locate executable programs, and LD_PRELOAD may be used to locate a separate library.
In various Microsoft-based systems, the PATH environment variable is consulted to locate a DLL, if the DLL is not found in other paths that appear earlier in the search order.

Alternate Terms

Untrusted Path

Common Consequences

Impact	Details
Gain Privileges or Assume Identity; Execute Unauthorized Code or Commands	Scope: Integrity, Confidentiality, Availability, Access Control There is the potential for arbitrary code execution with privileges of the vulnerable program.
DoS: Crash, Exit, or Restart	Scope: Availability The program could be redirected to the wrong files, potentially triggering a crash or hang when the targeted file is too large or does not have the expected format.
Read Files or Directories	Scope: Confidentiality The program could send the output of unauthorized files to the attacker.

Potential Mitigations

Phase(s)	Mitigation
Architecture and Design; Implementation	Strategy: Attack Surface Reduction Hard-code the search path to a set of known-safe values (such as system directories), or only allow them to be specified by the administrator in a configuration file. Do not allow these settings to be modified by an external party. Be careful to avoid related weaknesses such as CWE-426 and CWE-428.
Implementation	When invoking other programs, specify those programs using fully-qualified pathnames. While this is an effective approach, code that uses fully-qualified pathnames might not be portable to other systems that do not use the same pathnames. The portability can be improved by locating the full-qualified paths in a centralized, easily-modifiable location within the source code, and having the code refer to these paths.
Implementation	Remove or restrict all environment settings before invoking other programs. This includes the PATH environment variable, LD_LIBRARY_PATH, and other settings that identify the location of code libraries, and any application-specific search paths.
Implementation	Check your search path before use and remove any elements that are likely to be unsafe, such as the current working directory or a temporary files directory.
Implementation	Use other functions that require explicit paths. Making use of any of the other readily available functions that require explicit paths is a safe way to avoid this problem. For example, system() in C does not require a full path since the shell can take care of it, while execl() and execv() require a full path.

Relationships

Relevant to the view "Research Concepts" (View-1000)

Nature	Type	ID	Name
ChildOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	642	External Control of Critical State Data
ChildOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	673	External Influence of Sphere Definition
PeerOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	427	Uncontrolled Search Path Element
PeerOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	428	Unquoted Search Path or Element

Relevant to the view "Software Development" (View-699)

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1219	File Handling Issues

Relevant to the view "Weaknesses for Simplified Mapping of Published Vulnerabilities" (View-1003)

Nature	Type	ID	Name
ChildOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	668	Exposure of Resource to Wrong Sphere

Relevant to the view "Architectural Concepts" (View-1008)

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1011	Authorize Actors

Modes Of Introduction

Phase	Note
Implementation

Applicable Platforms

Languages	Class: Not Language-Specific (Undetermined Prevalence)
Operating Systems	Class: Not OS-Specific (Undetermined Prevalence)

Likelihood Of Exploit

High

Demonstrative Examples

Example 1

This program is intended to execute a command that lists the contents of a restricted directory, then performs other actions. Assume that it runs with setuid privileges in order to bypass the permissions check by the operating system.

(bad code)

Example Language: C

#define DIR "/restricted/directory"

char cmd[500];
sprintf(cmd, "ls -l %480s", DIR);
/* Raise privileges to those needed for accessing DIR. */

RaisePrivileges(...);
system(cmd);
DropPrivileges(...);
...

This code may look harmless at first, since both the directory and the command are set to fixed values that the attacker can't control. The attacker can only see the contents for DIR, which is the intended program behavior. Finally, the programmer is also careful to limit the code that executes with raised privileges.

However, because the program does not modify the PATH environment variable, the following attack would work:

(attack code)

The user sets the PATH to reference a directory under the attacker's control, such as "/my/dir/".
The attacker creates a malicious program called "ls", and puts that program in /my/dir
The user executes the program.
When system() is executed, the shell consults the PATH to find the ls program
The program finds the attacker's malicious program, "/my/dir/ls". It doesn't find "/bin/ls" because PATH does not contain "/bin/".
The program executes the attacker's malicious program with the raised privileges.

Example 2

The following code from a system utility uses the system property APPHOME to determine the directory in which it is installed and then executes an initialization script based on a relative path from the specified directory.

(bad code)

Example Language: Java

...
String home = System.getProperty("APPHOME");
String cmd = home + INITCMD;
java.lang.Runtime.getRuntime().exec(cmd);
...

The code above allows an attacker to execute arbitrary commands with the elevated privilege of the application by modifying the system property APPHOME to point to a different path containing a malicious version of INITCMD. Because the program does not validate the value read from the environment, if an attacker can control the value of the system property APPHOME, then they can fool the application into running malicious code and take control of the system.

Example 3

This code prints all of the running processes belonging to the current user.

(bad code)

Example Language: PHP

//assume getCurrentUser() returns a username that is guaranteed to be alphanumeric (avoiding CWE-78)
$userName = getCurrentUser();
$command = 'ps aux | grep ' . $userName;
system($command);

If invoked by an unauthorized web user, it is providing a web page of potentially sensitive information on the underlying system, such as command-line arguments (CWE-497). This program is also potentially vulnerable to a PATH based attack (CWE-426), as an attacker may be able to create malicious versions of the ps or grep commands. While the program does not explicitly raise privileges to run the system commands, the PHP interpreter may by default be running with higher privileges than users.

Example 4

The following code is from a web application that allows users access to an interface through which they can update their password on the system. In this environment, user passwords can be managed using the Network Information System (NIS), which is commonly used on UNIX systems. When performing NIS updates, part of the process for updating passwords is to run a make command in the /var/yp directory. Performing NIS updates requires extra privileges.

(bad code)

Example Language: Java

...
System.Runtime.getRuntime().exec("make");
...

The problem here is that the program does not specify an absolute path for make and does not clean its environment prior to executing the call to Runtime.exec(). If an attacker can modify the $PATH variable to point to a malicious binary called make and cause the program to be executed in their environment, then the malicious binary will be loaded instead of the one intended. Because of the nature of the application, it runs with the privileges necessary to perform system operations, which means the attacker's make will now be run with these privileges, possibly giving the attacker complete control of the system.

Selected Observed Examples

Reference	Description
CVE-1999-1120	Application relies on its PATH environment variable to find and execute program.
CVE-2008-1810	Database application relies on its PATH environment variable to find and execute program.
CVE-2007-2027	Chain: untrusted search path enabling resultant format string by loading malicious internationalization messages.
CVE-2008-3485	Untrusted search path using malicious .EXE in Windows environment.
CVE-2008-2613	setuid program allows compromise using path that finds and loads a malicious library.
CVE-2008-1319	Server allows client to specify the search path, which can be modified to point to a program that the client has uploaded.

Detection Methods

Method	Details
Black Box	Use monitoring tools that examine the software's process as it interacts with the operating system and the network. This technique is useful in cases when source code is unavailable, if the software was not developed by you, or if you want to verify that the build phase did not introduce any new weaknesses. Examples include debuggers that directly attach to the running process; system-call tracing utilities such as truss (Solaris) and strace (Linux); system activity monitors such as FileMon, RegMon, Process Monitor, and other Sysinternals utilities (Windows); and sniffers and protocol analyzers that monitor network traffic. Attach the monitor to the process and look for library functions and system calls that suggest when a search path is being used. One pattern is when the program performs multiple accesses of the same file but in different directories, with repeated failures until the proper filename is found. Library calls such as getenv() or their equivalent can be checked to see if any path-related variables are being accessed.
Automated Static Analysis	Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.) Effectiveness: High
Manual Analysis	Use tools and techniques that require manual (human) analysis, such as penetration testing, threat modeling, and interactive tools that allow the tester to record and modify an active session. These may be more effective than strictly automated techniques. This is especially the case with weaknesses that are related to design and business rules.

Functional Areas

Program Invocation
Code Libraries

Affected Resources

System Process

Memberships

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	744	CERT C Secure Coding Standard (2008) Chapter 11 - Environment (ENV)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	752	2009 Top 25 - Risky Resource Management
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	808	2010 Top 25 - Weaknesses On the Cusp
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	878	CERT C++ Secure Coding Section 10 - Environment (ENV)
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1200	Weaknesses in the 2019 CWE Top 25 Most Dangerous Software Errors
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1354	OWASP Top Ten 2021 Category A08:2021 - Software and Data Integrity Failures
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1403	Comprehensive Categorization: Exposed Resource

Vulnerability Mapping Notes

Usage	ALLOWED-WITH-REVIEW (this CWE ID could be used to map to real-world vulnerabilities in limited situations requiring careful review)
Reasons	Frequent Misinterpretation, Abstraction, Other
Rationale	This CWE entry is often confused with another closely-related entry about search paths.
Comments	CWE-426 and CWE-427 are often misused because they both mention search paths, although CWE-426 is focused on attacker control of the search path itself, while CWE-427 applies when the attacker cannot modify the search path but can write to one of the locations specified in the search path. Also, this entry is classified in a part of CWE's hierarchy that does not have sufficiently low-level coverage, which might reflect a lack of classification-oriented weakness research in the software security community. Conduct careful root cause analysis to determine the original mistake that led to this weakness. If closer analysis reveals that this weakness is appropriate, then this might be the best available CWE to use for mapping. If no other option is available, then it is acceptable to map to this CWE.

Taxonomy Mappings

Mapped Taxonomy Name	Node ID	Mapped Node Name
PLOVER		Untrusted Search Path
CLASP		Relative path library search
CERT C Secure Coding	ENV03-C	Sanitize the environment when invoking external programs

Related Attack Patterns

CAPEC-ID	Attack Pattern Name
CAPEC-38	Leveraging/Manipulating Configuration File Search Paths

References

[REF-18]	Secure Software, Inc.. "The CLASP Application Security Process". 2005. <https://cwe.mitre.org/documents/sources/TheCLASPApplicationSecurityProcess.pdf>. (URL validated: 2024-11-17)
[REF-62]	Mark Dowd, John McDonald and Justin Schuh. "The Art of Software Security Assessment". Chapter 10, Process Attributes, page 603. 1st Edition. Addison Wesley. 2006.
[REF-176]	Michael Howard and David LeBlanc. "Writing Secure Code". Chapter 8, "Canonical Representation Issues." Page 229. 1st Edition. Microsoft Press. 2001-11-13.
[REF-207]	John Viega and Gary McGraw. "Building Secure Software: How to Avoid Security Problems the Right Way". Chapter 12, "Trust Management and Input Validation." Pages 317-320. 1st Edition. Addison-Wesley. 2002.
[REF-7]	Michael Howard and David LeBlanc. "Writing Secure Code". Chapter 11, "Don't Trust the PATH - Use Full Path Names" Page 385. 2nd Edition. Microsoft Press. 2002-12-04. <https://www.microsoftpressstore.com/store/writing-secure-code-9780735617223>.

Content History

Submissions
Submission Date	Submitter	Organization
2006-07-19 (CWE Draft 3, 2006-07-19)	PLOVER
2006-07-19 (CWE Draft 3, 2006-07-19)
Modifications
Modification Date	Modifier	Organization
2025-04-03 (CWE 4.17, 2025-04-03)	CWE Content Team	MITRE
2025-04-03 (CWE 4.17, 2025-04-03)	updated Mapping_Notes
2024-07-16 (CWE 4.15, 2024-07-16)	CWE Content Team	MITRE
2024-07-16 (CWE 4.15, 2024-07-16)	updated Demonstrative_Examples
2023-06-29	CWE Content Team	MITRE
2023-06-29	updated Mapping_Notes
2023-04-27	CWE Content Team	MITRE
2023-04-27	updated Detection_Factors, Relationships, Time_of_Introduction
2023-01-31	CWE Content Team	MITRE
2023-01-31	updated Description
2022-04-28	CWE Content Team	MITRE
2022-04-28	updated Research_Gaps
2021-10-28	CWE Content Team	MITRE
2021-10-28	updated Relationships
2021-03-15	CWE Content Team	MITRE
2021-03-15	updated Demonstrative_Examples
2020-02-24	CWE Content Team	MITRE
2020-02-24	updated References, Relationships
2019-09-19	CWE Content Team	MITRE
2019-09-19	updated Relationships
2019-06-20	CWE Content Team	MITRE
2019-06-20	updated Related_Attack_Patterns, Relationships
2019-01-03	CWE Content Team	MITRE
2019-01-03	updated Related_Attack_Patterns
2018-03-27	CWE Content Team	MITRE
2018-03-27	updated Demonstrative_Examples, References, Relationships, Type
2017-11-08	CWE Content Team	MITRE
2017-11-08	updated Demonstrative_Examples, Modes_of_Introduction, References, Relationships, Taxonomy_Mappings
2015-12-07	CWE Content Team	MITRE
2015-12-07	updated Relationships
2014-02-18	CWE Content Team	MITRE
2014-02-18	updated Demonstrative_Examples, Detection_Factors, Potential_Mitigations
2012-05-11	CWE Content Team	MITRE
2012-05-11	updated Demonstrative_Examples, References
2011-09-13	CWE Content Team	MITRE
2011-09-13	updated Relationships, Taxonomy_Mappings
2011-06-01	CWE Content Team	MITRE
2011-06-01	updated Common_Consequences
2011-03-29	CWE Content Team	MITRE
2011-03-29	updated Demonstrative_Examples
2010-09-27	CWE Content Team	MITRE
2010-09-27	updated Description, Relationships
2010-06-21	CWE Content Team	MITRE
2010-06-21	updated Detection_Factors, Potential_Mitigations
2010-04-05	CWE Content Team	MITRE
2010-04-05	updated Applicable_Platforms
2010-02-16	CWE Content Team	MITRE
2010-02-16	updated References, Relationships
2009-12-28	CWE Content Team	MITRE
2009-12-28	updated References
2009-03-10	CWE Content Team	MITRE
2009-03-10	updated Demonstrative_Examples, Potential_Mitigations
2009-01-12	CWE Content Team	MITRE
2009-01-12	updated Applicable_Platforms, Common_Consequences, Demonstrative_Examples, Description, Observed_Examples, Potential_Mitigations, Relationships, Time_of_Introduction
2008-11-24	CWE Content Team	MITRE
2008-11-24	updated Relationships, Taxonomy_Mappings
2008-09-08	CWE Content Team	MITRE
2008-09-08	updated Common_Consequences, Relationships, Taxonomy_Mappings
2008-07-01	Eric Dalci	Cigital
2008-07-01	updated Time_of_Introduction

Weakness ID: 416

View customized information:

Description

Alternate Terms

Dangling pointer	a pointer that no longer points to valid memory, often after it has been freed
UAF	commonly used acronym for Use After Free
Use-After-Free

Common Consequences

Impact	Details
Modify Memory	Scope: Integrity The use of previously freed memory may corrupt valid data, if the memory area in question has been allocated and used properly elsewhere.
DoS: Crash, Exit, or Restart	Scope: Availability If chunk consolidation occurs after the use of previously freed data, the process may crash when invalid data is used as chunk information.
Execute Unauthorized Code or Commands	Scope: Integrity, Confidentiality, Availability If malicious data is entered before chunk consolidation can take place, it may be possible to take advantage of a write-what-where primitive to execute arbitrary code. If the newly allocated data happens to hold a class, in C++ for example, various function pointers may be scattered within the heap data. If one of these function pointers is overwritten with an address to valid shellcode, execution of arbitrary code can be achieved.

Potential Mitigations

Phase(s)

Mitigation

Architecture and Design

Strategy: Language Selection

Choose a language that provides automatic memory management.

Implementation

Strategy: Attack Surface Reduction

When freeing pointers, be sure to set them to NULL once they are freed. However, the utilization of multiple or complex data structures may lower the usefulness of this strategy.

Effectiveness: Defense in Depth

Note: If a bug causes an attempted access of this pointer, then a NULL dereference could still lead to a crash or other unexpected behavior, but it will reduce or eliminate the risk of code execution.

Relationships

Relevant to the view "Research Concepts" (View-1000)

Nature	Type	ID	Name
ChildOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	825	Expired Pointer Dereference
PeerOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	415	Double Free
CanFollow	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	362	Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
CanFollow	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	364	Signal Handler Race Condition
CanFollow	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	754	Improper Check for Unusual or Exceptional Conditions
CanFollow	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	1265	Unintended Reentrant Invocation of Non-reentrant Code Via Nested Calls
CanPrecede	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	120	Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
CanPrecede	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	123	Write-what-where Condition

Relevant to the view "Weaknesses for Simplified Mapping of Published Vulnerabilities" (View-1003)

Nature	Type	ID	Name
ChildOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	672	Operation on a Resource after Expiration or Release

Relevant to the view "CISQ Quality Measures (2020)" (View-1305)

Nature	Type	ID	Name
ChildOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	672	Operation on a Resource after Expiration or Release

Relevant to the view "CISQ Data Protection Measures" (View-1340)

Nature	Type	ID	Name
ChildOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	672	Operation on a Resource after Expiration or Release

Modes Of Introduction

Phase	Note
Implementation

Applicable Platforms

Languages

C (Undetermined Prevalence)

C++ (Undetermined Prevalence)

Likelihood Of Exploit

High

Demonstrative Examples

Example 1

The following example demonstrates the weakness.

(bad code)

Example Language: C

#include <stdio.h>
#include <unistd.h>
#define BUFSIZER1 512
#define BUFSIZER2 ((BUFSIZER1/2) - 8)
int main(int argc, char **argv) {

char *buf1R1;
char *buf2R1;
char *buf2R2;
char *buf3R2;
buf1R1 = (char *) malloc(BUFSIZER1);
buf2R1 = (char *) malloc(BUFSIZER1);
free(buf2R1);
buf2R2 = (char *) malloc(BUFSIZER2);
buf3R2 = (char *) malloc(BUFSIZER2);
strncpy(buf2R1, argv[1], BUFSIZER1-1);
free(buf1R1);
free(buf2R2);
free(buf3R2);

}

Example 2

The following code illustrates a use after free error:

(bad code)

Example Language: C

char* ptr = (char*)malloc (SIZE);
if (err) {

abrt = 1;
free(ptr);

}
...
if (abrt) {

logError("operation aborted before commit", ptr);

}

When an error occurs, the pointer is immediately freed. However, this pointer is later incorrectly used in the logError function.

Selected Observed Examples

Reference	Description
CVE-2022-20141	Chain: an operating system kernel has insufficent resource locking (CWE-413) leading to a use after free (CWE-416).
CVE-2022-2621	Chain: two threads in a web browser use the same resource (CWE-366), but one of those threads can destroy the resource before the other has completed (CWE-416).
CVE-2021-0920	Chain: mobile platform race condition (CWE-362) leading to use-after-free (CWE-416), as exploited in the wild per CISA KEV.
CVE-2020-6819	Chain: race condition (CWE-362) leads to use-after-free (CWE-416), as exploited in the wild per CISA KEV.
CVE-2010-4168	Use-after-free triggered by closing a connection while data is still being transmitted.
CVE-2010-2941	Improper allocation for invalid data leads to use-after-free.
CVE-2010-2547	certificate with a large number of Subject Alternate Names not properly handled in realloc, leading to use-after-free
CVE-2010-1772	Timers are not disabled when a related object is deleted
CVE-2010-1437	Access to a "dead" object that is being cleaned up
CVE-2010-1208	object is deleted even with a non-zero reference count, and later accessed
CVE-2010-0629	use-after-free involving request containing an invalid version number
CVE-2010-0378	unload of an object that is currently being accessed by other functionality
CVE-2010-0302	incorrectly tracking a reference count leads to use-after-free
CVE-2010-0249	use-after-free related to use of uninitialized memory
CVE-2010-0050	HTML document with incorrectly-nested tags
CVE-2009-3658	Use after free in ActiveX object by providing a malformed argument to a method
CVE-2009-3616	use-after-free by disconnecting during data transfer, or a message containing incorrect data types
CVE-2009-3553	disconnect during a large data transfer causes incorrect reference count, leading to use-after-free
CVE-2009-2416	use-after-free found by fuzzing
CVE-2009-1837	Chain: race condition (CWE-362) from improper handling of a page transition in web client while an applet is loading (CWE-368) leads to use after free (CWE-416)
CVE-2009-0749	realloc generates new buffer and pointer, but previous pointer is still retained, leading to use after free
CVE-2010-3328	Use-after-free in web browser, probably resultant from not initializing memory.
CVE-2008-5038	use-after-free when one thread accessed memory that was freed by another thread
CVE-2008-0077	assignment of malformed values to certain properties triggers use after free
CVE-2006-4434	mail server does not properly handle a long header.
CVE-2010-2753	chain: integer overflow leads to use-after-free
CVE-2006-4997	freed pointer dereference
CVE-2003-0813	Chain: A multi-threaded race condition (CWE-367) allows attackers to cause two threads to process the same RPC request, which causes a use-after-free (CWE-416) in one thread

Weakness Ordinalities

Ordinality

Description

Resultant

(where the weakness is typically related to the presence of some other weaknesses)

If the product accesses a previously-freed pointer, then it means that a separate weakness or error already occurred previously, such as a race condition, an unexpected or poorly handled error condition, confusion over which part of the program is responsible for freeing the memory, performing the free too soon, etc.

Detection Methods

Method

Details

Fuzzing

Fuzz testing (fuzzing) is a powerful technique for generating large numbers of diverse inputs - either randomly or algorithmically - and dynamically invoking the code with those inputs. Even with random inputs, it is often capable of generating unexpected results such as crashes, memory corruption, or resource consumption. Fuzzing effectively produces repeatable test cases that clearly indicate bugs, which helps developers to diagnose the issues.

Effectiveness: High

Automated Static Analysis

Effectiveness: High

Affected Resources

Memory

Memberships

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	398	7PK - Code Quality
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	742	CERT C Secure Coding Standard (2008) Chapter 9 - Memory Management (MEM)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	808	2010 Top 25 - Weaknesses On the Cusp
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	876	CERT C++ Secure Coding Section 08 - Memory Management (MEM)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	983	SFP Secondary Cluster: Faulty Resource Use
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1162	SEI CERT C Coding Standard - Guidelines 08. Memory Management (MEM)
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1200	Weaknesses in the 2019 CWE Top 25 Most Dangerous Software Errors
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1337	Weaknesses in the 2021 CWE Top 25 Most Dangerous Software Weaknesses
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1350	Weaknesses in the 2020 CWE Top 25 Most Dangerous Software Weaknesses
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1387	Weaknesses in the 2022 CWE Top 25 Most Dangerous Software Weaknesses
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1399	Comprehensive Categorization: Memory Safety
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1425	Weaknesses in the 2023 CWE Top 25 Most Dangerous Software Weaknesses
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1430	Weaknesses in the 2024 CWE Top 25 Most Dangerous Software Weaknesses

Vulnerability Mapping Notes

Usage	ALLOWED (this CWE ID may be used to map to real-world vulnerabilities)
Reason	Acceptable-Use
Rationale	This CWE entry is at the Variant level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.
Comments	Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction.

Taxonomy Mappings

Mapped Taxonomy Name	Node ID	Fit	Mapped Node Name
ISA/IEC 62443	Part 4-1		Req SI-1
7 Pernicious Kingdoms			Use After Free
CLASP			Using freed memory
CERT C Secure Coding	MEM00-C		Allocate and free memory in the same module, at the same level of abstraction
CERT C Secure Coding	MEM01-C		Store a new value in pointers immediately after free()
CERT C Secure Coding	MEM30-C	Exact	Do not access freed memory
Software Fault Patterns	SFP15		Faulty Resource Use

References

[REF-6]	Katrina Tsipenyuk, Brian Chess and Gary McGraw. "Seven Pernicious Kingdoms: A Taxonomy of Software Security Errors". NIST Workshop on Software Security Assurance Tools Techniques and Metrics. NIST. 2005-11-07. <https://samate.nist.gov/SSATTM_Content/papers/Seven%20Pernicious%20Kingdoms%20-%20Taxonomy%20of%20Sw%20Security%20Errors%20-%20Tsipenyuk%20-%20Chess%20-%20McGraw.pdf>.
[REF-18]	Secure Software, Inc.. "The CLASP Application Security Process". 2005. <https://cwe.mitre.org/documents/sources/TheCLASPApplicationSecurityProcess.pdf>. (URL validated: 2024-11-17)
[REF-44]	Michael Howard, David LeBlanc and John Viega. "24 Deadly Sins of Software Security". "Sin 8: C++ Catastrophes." Page 143. McGraw-Hill. 2010.

Content History

Submissions
Submission Date	Submitter	Organization
2006-07-19 (CWE Draft 3, 2006-07-19)	7 Pernicious Kingdoms
2006-07-19 (CWE Draft 3, 2006-07-19)
Contributions
Contribution Date	Contributor	Organization
2022-06-28	Anonymous External Contributor
2022-06-28	Suggested rephrase for extended description
2023-11-14 (CWE 4.14, 2024-02-29)	participants in the CWE ICS/OT SIG 62443 Mapping Fall Workshop
2023-11-14 (CWE 4.14, 2024-02-29)	Contributed or reviewed taxonomy mappings for ISA/IEC 62443
2024-02-29 (CWE 4.15, 2024-07-16)	Abhi Balakrishnan
2024-02-29 (CWE 4.15, 2024-07-16)	Provided diagram to improve CWE usability
Modifications
Modification Date	Modifier	Organization
2025-04-03 (CWE 4.17, 2025-04-03)	CWE Content Team	MITRE
2025-04-03 (CWE 4.17, 2025-04-03)	updated Observed_Examples
2024-11-19 (CWE 4.16, 2024-11-19)	CWE Content Team	MITRE
2024-11-19 (CWE 4.16, 2024-11-19)	updated Relationships
2024-07-16 (CWE 4.15, 2024-07-16)	CWE Content Team	MITRE
2024-07-16 (CWE 4.15, 2024-07-16)	updated Alternate_Terms, Common_Consequences, Description, Diagram, Potential_Mitigations, Relationships, Weakness_Ordinalities
2024-02-29 (CWE 4.14, 2024-02-29)	CWE Content Team	MITRE
2024-02-29 (CWE 4.14, 2024-02-29)	updated Taxonomy_Mappings
2023-10-26	CWE Content Team	MITRE
2023-10-26	updated Observed_Examples
2023-06-29	CWE Content Team	MITRE
2023-06-29	updated Mapping_Notes, Relationships
2023-04-27	CWE Content Team	MITRE
2023-04-27	updated Detection_Factors, Relationships, Time_of_Introduction
2022-10-13	CWE Content Team	MITRE
2022-10-13	updated Description, Relationships, Taxonomy_Mappings
2022-06-28	CWE Content Team	MITRE
2022-06-28	updated Observed_Examples, Relationships
2021-07-20	CWE Content Team	MITRE
2021-07-20	updated Relationships
2020-12-10	CWE Content Team	MITRE
2020-12-10	updated Relationships
2020-08-20	CWE Content Team	MITRE
2020-08-20	updated Relationships
2020-06-25	CWE Content Team	MITRE
2020-06-25	updated Relationships
2020-02-24	CWE Content Team	MITRE
2020-02-24	updated References, Relationships, Taxonomy_Mappings
2019-09-19	CWE Content Team	MITRE
2019-09-19	updated Relationships
2019-06-20	CWE Content Team	MITRE
2019-06-20	updated Relationships, Type
2019-01-03	CWE Content Team	MITRE
2019-01-03	updated Relationships
2017-11-08	CWE Content Team	MITRE
2017-11-08	updated Demonstrative_Examples, Relationships, Taxonomy_Mappings, White_Box_Definitions
2015-12-07	CWE Content Team	MITRE
2015-12-07	updated Relationships
2014-07-30	CWE Content Team	MITRE
2014-07-30	updated Relationships, Taxonomy_Mappings
2012-05-11	CWE Content Team	MITRE
2012-05-11	updated References, Relationships
2011-09-13	CWE Content Team	MITRE
2011-09-13	updated Relationships, Taxonomy_Mappings
2011-06-27	CWE Content Team	MITRE
2011-06-27	updated Demonstrative_Examples
2011-06-01	CWE Content Team	MITRE
2011-06-01	updated Common_Consequences
2011-03-29	CWE Content Team	MITRE
2011-03-29	updated Description
2010-12-13	CWE Content Team	MITRE
2010-12-13	updated Alternate_Terms, Common_Consequences, Description, Observed_Examples, Other_Notes, Potential_Mitigations, Relationships
2010-09-27	CWE Content Team	MITRE
2010-09-27	updated Observed_Examples, Relationships
2010-06-21	CWE Content Team	MITRE
2010-06-21	updated Potential_Mitigations
2010-02-16	CWE Content Team	MITRE
2010-02-16	updated Relationships
2009-10-29	CWE Content Team	MITRE
2009-10-29	updated Common_Consequences
2009-05-27	CWE Content Team	MITRE
2009-05-27	updated Demonstrative_Examples
2009-03-10	CWE Content Team	MITRE
2009-03-10	updated Demonstrative_Examples
2008-11-24	CWE Content Team	MITRE
2008-11-24	updated Relationships, Taxonomy_Mappings
2008-09-08	CWE Content Team	MITRE
2008-09-08	updated Applicable_Platforms, Common_Consequences, Relationships, Observed_Example, Other_Notes, Taxonomy_Mappings
2008-08-01		KDM Analytics
2008-08-01	added/updated white box definitions
2008-07-01	Eric Dalci	Cigital
2008-07-01	updated Potential_Mitigations, Time_of_Introduction

Weakness ID: 327

Vulnerability Mapping: ALLOWED This CWE ID could be used to map to real-world vulnerabilities in limited situations requiring careful review (with careful review of mapping notes)
Abstraction: Class Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.

View customized information:

Description

The product uses a broken or risky cryptographic algorithm or protocol.

Extended Description

Cryptographic algorithms are the methods by which data is scrambled to prevent observation or influence by unauthorized actors. Insecure cryptography can be exploited to expose sensitive information, modify data in unexpected ways, spoof identities of other users or devices, or other impacts.

It is very difficult to produce a secure algorithm, and even high-profile algorithms by accomplished cryptographic experts have been broken. Well-known techniques exist to break or weaken various kinds of cryptography. Accordingly, there are a small number of well-understood and heavily studied algorithms that should be used by most products. Using a non-standard or known-insecure algorithm is dangerous because a determined adversary may be able to break the algorithm and compromise whatever data has been protected.

Since the state of cryptography advances so rapidly, it is common for an algorithm to be considered "unsafe" even if it was once thought to be strong. This can happen when new attacks are discovered, or if computing power increases so much that the cryptographic algorithm no longer provides the amount of protection that was originally thought.

For a number of reasons, this weakness is even more challenging to manage with hardware deployment of cryptographic algorithms as opposed to software implementation. First, if a flaw is discovered with hardware-implemented cryptography, the flaw cannot be fixed in most cases without a recall of the product, because hardware is not easily replaceable like software. Second, because the hardware product is expected to work for years, the adversary's computing power will only increase over time.

Common Consequences

Impact	Details
Read Application Data	Scope: Confidentiality The confidentiality of sensitive data may be compromised by the use of a broken or risky cryptographic algorithm.
Modify Application Data	Scope: Integrity The integrity of sensitive data may be compromised by the use of a broken or risky cryptographic algorithm.
Hide Activities	Scope: Accountability, Non-Repudiation If the cryptographic algorithm is used to ensure the identity of the source of the data (such as digital signatures), then a broken algorithm will compromise this scheme and the source of the data cannot be proven.

Potential Mitigations

Phase(s)	Mitigation
Architecture and Design	Strategy: Libraries or Frameworks When there is a need to store or transmit sensitive data, use strong, up-to-date cryptographic algorithms to encrypt that data. Select a well-vetted algorithm that is currently considered to be strong by experts in the field, and use well-tested implementations. As with all cryptographic mechanisms, the source code should be available for analysis. For example, US government systems require FIPS 140-2 certification [REF-1192]. Do not develop custom or private cryptographic algorithms. They will likely be exposed to attacks that are well-understood by cryptographers. Reverse engineering techniques are mature. If the algorithm can be compromised if attackers find out how it works, then it is especially weak. Periodically ensure that the cryptography has not become obsolete. Some older algorithms, once thought to require a billion years of computing time, can now be broken in days or hours. This includes MD4, MD5, SHA1, DES, and other algorithms that were once regarded as strong. [REF-267]
Architecture and Design	Ensure that the design allows one cryptographic algorithm to be replaced with another in the next generation or version. Where possible, use wrappers to make the interfaces uniform. This will make it easier to upgrade to stronger algorithms. With hardware, design the product at the Intellectual Property (IP) level so that one cryptographic algorithm can be replaced with another in the next generation of the hardware product. Effectiveness: Defense in Depth
Architecture and Design	Carefully manage and protect cryptographic keys (see CWE-320). If the keys can be guessed or stolen, then the strength of the cryptography itself is irrelevant.
Architecture and Design	Strategy: Libraries or Frameworks Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. Industry-standard implementations will save development time and may be more likely to avoid errors that can occur during implementation of cryptographic algorithms. Consider the ESAPI Encryption feature.
Implementation; Architecture and Design	When using industry-approved techniques, use them correctly. Don't cut corners by skipping resource-intensive steps (CWE-325). These steps are often essential for preventing common attacks.

Relationships

Relevant to the view "Research Concepts" (View-1000)

Nature	Type	ID	Name
ChildOf	Pillar - a weakness that is the most abstract type of weakness and represents a theme for all class/base/variant weaknesses related to it. A Pillar is different from a Category as a Pillar is still technically a type of weakness that describes a mistake, while a Category represents a common characteristic used to group related things.	693	Protection Mechanism Failure
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	328	Use of Weak Hash
ParentOf	Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	780	Use of RSA Algorithm without OAEP
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	1240	Use of a Cryptographic Primitive with a Risky Implementation
PeerOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	301	Reflection Attack in an Authentication Protocol
PeerOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	311	Missing Encryption of Sensitive Data
CanFollow	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	208	Observable Timing Discrepancy

Relevant to the view "Weaknesses for Simplified Mapping of Published Vulnerabilities" (View-1003)

Nature	Type	ID	Name
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1003	Weaknesses for Simplified Mapping of Published Vulnerabilities
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	916	Use of Password Hash With Insufficient Computational Effort

Relevant to the view "Architectural Concepts" (View-1008)

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1013	Encrypt Data

Modes Of Introduction

Phase

Note

Architecture and Design

COMMISSION: This weakness refers to an incorrect design related to an architectural security tactic.

Implementation

With hardware, the Architecture or Design Phase might start with compliant cryptography, but it is replaced with a non-compliant crypto during the later Implementation phase due to implementation constraints (e.g., not enough entropy to make it function properly, or not enough silicon real estate available to implement). Or, in rare cases (especially for long projects that span over years), the Architecture specifications might start with cryptography that was originally compliant at the time the Architectural specs were written, but over the time it became non-compliant due to progress made in attacking the crypto.

Applicable Platforms

Languages	Class: Not Language-Specific (Undetermined Prevalence) Verilog (Undetermined Prevalence) VHDL (Undetermined Prevalence)
Technologies	Class: Not Technology-Specific (Undetermined Prevalence) Class: ICS/OT (Undetermined Prevalence)

Likelihood Of Exploit

High

Demonstrative Examples

Example 1

These code examples use the Data Encryption Standard (DES).

(bad code)

Example Language: C

EVP_des_ecb();

(bad code)

Example Language: Java

Cipher des=Cipher.getInstance("DES...");
des.initEncrypt(key2);

(bad code)

Example Language: PHP

function encryptPassword($password){

$iv_size = mcrypt_get_iv_size(MCRYPT_DES, MCRYPT_MODE_ECB);
$iv = mcrypt_create_iv($iv_size, MCRYPT_RAND);
$key = "This is a password encryption key";
$encryptedPassword = mcrypt_encrypt(MCRYPT_DES, $key, $password, MCRYPT_MODE_ECB, $iv);
return $encryptedPassword;

}

Once considered a strong algorithm, DES now regarded as insufficient for many applications. It has been replaced by Advanced Encryption Standard (AES).

Example 2

Suppose a chip manufacturer decides to implement a hashing scheme for verifying integrity property of certain bitstream, and it chooses to implement a SHA1 hardware accelerator for to implement the scheme.

(bad code)

Example Language: Other

The manufacturer chooses a SHA1 hardware accelerator for to implement the scheme because it already has a working SHA1 Intellectual Property (IP) that the manufacturer had created and used earlier, so this reuse of IP saves design cost.

However, SHA1 was theoretically broken in 2005 and practically broken in 2017 at a cost of $110K. This means an attacker with access to cloud-rented computing power will now be able to provide a malicious bitstream with the same hash value, thereby defeating the purpose for which the hash was used.

This issue could have been avoided with better design.

(good code)

Example Language: Other

The manufacturer could have chosen a cryptographic solution that is recommended by the wide security community (including standard-setting bodies like NIST) and is not expected to be broken (or even better, weakened) within the reasonable life expectancy of the hardware product. In this case, the architects could have used SHA-2 or SHA-3, even if it meant that such choice would cost extra.

Example 3

In 2022, the OT:ICEFALL study examined products by 10 different Operational Technology (OT) vendors. The researchers reported 56 vulnerabilities and said that the products were "insecure by design" [REF-1283]. If exploited, these vulnerabilities often allowed adversaries to change how the products operated, ranging from denial of service to changing the code that the products executed. Since these products were often used in industries such as power, electrical, water, and others, there could even be safety implications.

Multiple OT products used weak cryptography.

Selected Observed Examples

Reference	Description
CVE-2022-30273	SCADA-based protocol supports a legacy encryption mode that uses Tiny Encryption Algorithm (TEA) in ECB mode, which leaks patterns in messages and cannot protect integrity
CVE-2022-30320	Programmable Logic Controller (PLC) uses a protocol with a cryptographically insecure hashing algorithm for passwords.
CVE-2008-3775	Product uses "ROT-25" to obfuscate the password in the registry.
CVE-2007-4150	product only uses "XOR" to obfuscate sensitive data
CVE-2007-5460	product only uses "XOR" and a fixed key to obfuscate sensitive data
CVE-2005-4860	Product substitutes characters with other characters in a fixed way, and also leaves certain input characters unchanged.
CVE-2002-2058	Attackers can infer private IP addresses by dividing each octet by the MD5 hash of '20'.
CVE-2008-3188	Product uses DES when MD5 has been specified in the configuration, resulting in weaker-than-expected password hashes.
CVE-2005-2946	Default configuration of product uses MD5 instead of stronger algorithms that are available, simplifying forgery of certificates.
CVE-2007-6013	Product uses the hash of a hash for authentication, allowing attackers to gain privileges if they can obtain the original hash.

Detection Methods

Method	Details
Automated Analysis	Automated methods may be useful for recognizing commonly-used libraries or features that have become obsolete. Effectiveness: Moderate Note:False negatives may occur if the tool is not aware of the cryptographic libraries in use, or if custom cryptography is being used.
Manual Analysis	This weakness can be detected using tools and techniques that require manual (human) analysis, such as penetration testing, threat modeling, and interactive tools that allow the tester to record and modify an active session. Note:These may be more effective than strictly automated techniques. This is especially the case with weaknesses that are related to design and business rules.
Automated Static Analysis - Binary or Bytecode	According to SOAR, the following detection techniques may be useful: Cost effective for partial coverage: Bytecode Weakness Analysis - including disassembler + source code weakness analysis Binary Weakness Analysis - including disassembler + source code weakness analysis Binary / Bytecode simple extractor - strings, ELF readers, etc. Effectiveness: SOAR Partial
Manual Static Analysis - Binary or Bytecode	According to SOAR, the following detection techniques may be useful: Cost effective for partial coverage: Binary / Bytecode disassembler - then use manual analysis for vulnerabilities & anomalies Effectiveness: SOAR Partial
Dynamic Analysis with Automated Results Interpretation	According to SOAR, the following detection techniques may be useful: Cost effective for partial coverage: Web Application Scanner Web Services Scanner Database Scanners Effectiveness: SOAR Partial
Dynamic Analysis with Manual Results Interpretation	According to SOAR, the following detection techniques may be useful: Highly cost effective: Man-in-the-middle attack tool Cost effective for partial coverage: Framework-based Fuzzer Automated Monitored Execution Monitored Virtual Environment - run potentially malicious code in sandbox / wrapper / virtual machine, see if it does anything suspicious Effectiveness: High
Manual Static Analysis - Source Code	According to SOAR, the following detection techniques may be useful: Highly cost effective: Manual Source Code Review (not inspections) Cost effective for partial coverage: Focused Manual Spotcheck - Focused manual analysis of source Effectiveness: High
Automated Static Analysis - Source Code	According to SOAR, the following detection techniques may be useful: Highly cost effective: Source code Weakness Analyzer Context-configured Source Code Weakness Analyzer Effectiveness: High
Automated Static Analysis	According to SOAR, the following detection techniques may be useful: Cost effective for partial coverage: Configuration Checker Effectiveness: SOAR Partial
Architecture or Design Review	According to SOAR, the following detection techniques may be useful: Highly cost effective: Formal Methods / Correct-By-Construction Cost effective for partial coverage: Inspection (IEEE 1028 standard) (can apply to requirements, design, source code, etc.) Effectiveness: High

Memberships

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	729	OWASP Top Ten 2004 Category A8 - Insecure Storage
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	753	2009 Top 25 - Porous Defenses
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	803	2010 Top 25 - Porous Defenses
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	816	OWASP Top Ten 2010 Category A7 - Insecure Cryptographic Storage
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	866	2011 Top 25 - Porous Defenses
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	883	CERT C++ Secure Coding Section 49 - Miscellaneous (MSC)
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	884	CWE Cross-section
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	934	OWASP Top Ten 2013 Category A6 - Sensitive Data Exposure
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	958	SFP Secondary Cluster: Broken Cryptography
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1029	OWASP Top Ten 2017 Category A3 - Sensitive Data Exposure
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1131	CISQ Quality Measures (2016) - Security
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1152	SEI CERT Oracle Secure Coding Standard for Java - Guidelines 49. Miscellaneous (MSC)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1170	SEI CERT C Coding Standard - Guidelines 48. Miscellaneous (MSC)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1346	OWASP Top Ten 2021 Category A02:2021 - Cryptographic Failures
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1366	ICS Communications: Frail Security in Protocols
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1402	Comprehensive Categorization: Encryption

Vulnerability Mapping Notes

Usage	ALLOWED-WITH-REVIEW (this CWE ID could be used to map to real-world vulnerabilities in limited situations requiring careful review)
Reason	Abstraction
Rationale	This CWE entry is a Class and might have Base-level children that would be more appropriate
Comments	Examine children of this entry to see if there is a better fit

Notes

Maintenance

Since CWE 4.4, various cryptography-related entries, including CWE-327 and CWE-1240, have been slated for extensive research, analysis, and community consultation to define consistent terminology, improve relationships, and reduce overlap or duplication. As of CWE 4.6, this work is still ongoing.

Maintenance

The Taxonomy_Mappings to ISA/IEC 62443 were added in CWE 4.10, but they are still under review and might change in future CWE versions. These draft mappings were performed by members of the "Mapping CWE to 62443" subgroup of the CWE-CAPEC ICS/OT Special Interest Group (SIG), and their work is incomplete as of CWE 4.10. The mappings are included to facilitate discussion and review by the broader ICS/OT community, and they are likely to change in future CWE versions.

Taxonomy Mappings

Mapped Taxonomy Name	Node ID	Fit	Mapped Node Name
CLASP			Using a broken or risky cryptographic algorithm
OWASP Top Ten 2004	A8	CWE More Specific	Insecure Storage
CERT C Secure Coding	MSC30-C	CWE More Abstract	Do not use the rand() function for generating pseudorandom numbers
CERT C Secure Coding	MSC32-C	CWE More Abstract	Properly seed pseudorandom number generators
The CERT Oracle Secure Coding Standard for Java (2011)	MSC02-J		Generate strong random numbers
OMG ASCSM	ASCSM-CWE-327
ISA/IEC 62443	Part 3-3		Req SR 4.3
ISA/IEC 62443	Part 4-2		Req CR 4.3

Related Attack Patterns

CAPEC-ID	Attack Pattern Name
CAPEC-20	Encryption Brute Forcing
CAPEC-459	Creating a Rogue Certification Authority Certificate
CAPEC-473	Signature Spoof
CAPEC-475	Signature Spoofing by Improper Validation
CAPEC-608	Cryptanalysis of Cellular Encryption
CAPEC-614	Rooting SIM Cards
CAPEC-97	Cryptanalysis

References

[REF-280]	Bruce Schneier. "Applied Cryptography". John Wiley & Sons. 1996. <https://www.schneier.com/books/applied-cryptography>. (URL validated: 2023-04-07)
[REF-281]	Alfred J. Menezes, Paul C. van Oorschot and Scott A. Vanstone. "Handbook of Applied Cryptography". 1996-10. <https://cacr.uwaterloo.ca/hac/>. (URL validated: 2023-04-07)
[REF-282]	C Matthew Curtin. "Avoiding bogus encryption products: Snake Oil FAQ". 1998-04-10. <http://www.faqs.org/faqs/cryptography-faq/snake-oil/>.
[REF-267]	Information Technology Laboratory, National Institute of Standards and Technology. "SECURITY REQUIREMENTS FOR CRYPTOGRAPHIC MODULES". 2001-05-25. <https://csrc.nist.gov/csrc/media/publications/fips/140/2/final/documents/fips1402.pdf>. (URL validated: 2023-04-07)
[REF-284]	Paul F. Roberts. "Microsoft Scraps Old Encryption in New Code". 2005-09-15. <https://www.eweek.com/security/microsoft-scraps-old-encryption-in-new-code/>. (URL validated: 2023-04-07)
[REF-7]	Michael Howard and David LeBlanc. "Writing Secure Code". Chapter 8, "Cryptographic Foibles" Page 259. 2nd Edition. Microsoft Press. 2002-12-04. <https://www.microsoftpressstore.com/store/writing-secure-code-9780735617223>.
[REF-44]	Michael Howard, David LeBlanc and John Viega. "24 Deadly Sins of Software Security". "Sin 21: Using the Wrong Cryptography." Page 315. McGraw-Hill. 2010.
[REF-287]	Johannes Ullrich. "Top 25 Series - Rank 24 - Use of a Broken or Risky Cryptographic Algorithm". SANS Software Security Institute. 2010-03-25. <https://www.sans.org/blog/top-25-series-use-of-a-broken-or-risky-cryptographic-algorithm/>. (URL validated: 2023-04-07)
[REF-62]	Mark Dowd, John McDonald and Justin Schuh. "The Art of Software Security Assessment". Chapter 2, "Insufficient or Obsolete Encryption", Page 44. 1st Edition. Addison Wesley. 2006.
[REF-962]	Object Management Group (OMG). "Automated Source Code Security Measure (ASCSM)". ASCSM-CWE-327. 2016-01. <http://www.omg.org/spec/ASCSM/1.0/>.
[REF-18]	Secure Software, Inc.. "The CLASP Application Security Process". 2005. <https://cwe.mitre.org/documents/sources/TheCLASPApplicationSecurityProcess.pdf>. (URL validated: 2024-11-17)
[REF-1192]	Information Technology Laboratory, National Institute of Standards and Technology. "FIPS PUB 140-3: SECURITY REQUIREMENTS FOR CRYPTOGRAPHIC MODULES". 2019-03-22. <https://csrc.nist.gov/publications/detail/fips/140/3/final>.
[REF-1283]	Forescout Vedere Labs. "OT:ICEFALL: The legacy of "insecure by design" and its implications for certifications and risk management". 2022-06-20. <https://www.forescout.com/resources/ot-icefall-report/>.

Content History

Submissions
Submission Date	Submitter	Organization
2006-07-19 (CWE Draft 3, 2006-07-19)	CLASP
2006-07-19 (CWE Draft 3, 2006-07-19)
Contributions
Contribution Date	Contributor	Organization
2019-12-10	Parbati K. Manna	Intel Corporation
2019-12-10	Provide a hardware-specific submission whose contents were integrated into this entry, affecting extended description, applicable platforms, demonstrative examples, and mitigations
Modifications
Modification Date	Modifier	Organization
2023-06-29	CWE Content Team	MITRE
2023-06-29	updated Mapping_Notes, Relationships
2023-04-27	CWE Content Team	MITRE
2023-04-27	updated References, Relationships
2023-01-31	CWE Content Team	MITRE
2023-01-31	updated Applicable_Platforms, Background_Details, Demonstrative_Examples, Description, Maintenance_Notes, Modes_of_Introduction, Observed_Examples, Potential_Mitigations, References, Taxonomy_Mappings, Time_of_Introduction
2022-10-13	CWE Content Team	MITRE
2022-10-13	updated Demonstrative_Examples, Observed_Examples, References
2022-04-28	CWE Content Team	MITRE
2022-04-28	updated Relationships
2021-10-28	CWE Content Team	MITRE
2021-10-28	updated Maintenance_Notes, Potential_Mitigations, Relationships
2021-03-15	CWE Content Team	MITRE
2021-03-15	updated References
2020-02-24	CWE Content Team	MITRE
2020-02-24	updated Applicable_Platforms, Detection_Factors, Maintenance_Notes, Relationships
2019-06-20	CWE Content Team	MITRE
2019-06-20	updated Related_Attack_Patterns, Relationships, Type
2019-01-03	CWE Content Team	MITRE
2019-01-03	updated References, Relationships, Taxonomy_Mappings
2018-03-27	CWE Content Team	MITRE
2018-03-27	updated References, Relationships
2017-11-08	CWE Content Team	MITRE
2017-11-08	updated Demonstrative_Examples, Likelihood_of_Exploit, Modes_of_Introduction, References, Relationships, Taxonomy_Mappings
2017-01-19	CWE Content Team	MITRE
2017-01-19	updated Related_Attack_Patterns
2015-12-07	CWE Content Team	MITRE
2015-12-07	updated Relationships
2014-07-30	CWE Content Team	MITRE
2014-07-30	updated Demonstrative_Examples, Detection_Factors, Relationships
2014-06-23	CWE Content Team	MITRE
2014-06-23	updated Relationships
2014-02-18	CWE Content Team	MITRE
2014-02-18	updated Related_Attack_Patterns
2013-02-21	CWE Content Team	MITRE
2013-02-21	updated Relationships
2012-10-30	CWE Content Team	MITRE
2012-10-30	updated Potential_Mitigations
2012-05-11	CWE Content Team	MITRE
2012-05-11	updated References, Related_Attack_Patterns, Relationships, Taxonomy_Mappings
2011-09-13	CWE Content Team	MITRE
2011-09-13	updated Potential_Mitigations, Relationships, Taxonomy_Mappings
2011-06-27	CWE Content Team	MITRE
2011-06-27	updated Relationships
2011-06-01	CWE Content Team	MITRE
2011-06-01	updated Relationships, Taxonomy_Mappings
2011-03-29	CWE Content Team	MITRE
2011-03-29	updated Demonstrative_Examples, Description
2010-09-27	CWE Content Team	MITRE
2010-09-27	updated Potential_Mitigations, Relationships
2010-06-21	CWE Content Team	MITRE
2010-06-21	updated Common_Consequences, Detection_Factors, Potential_Mitigations, References, Relationships
2010-04-05	CWE Content Team	MITRE
2010-04-05	updated Applicable_Platforms, Potential_Mitigations, Related_Attack_Patterns
2010-02-16	CWE Content Team	MITRE
2010-02-16	updated Detection_Factors, References, Relationships
2009-12-28	CWE Content Team	MITRE
2009-12-28	updated References
2009-10-29	CWE Content Team	MITRE
2009-10-29	updated Relationships
2009-07-27	CWE Content Team	MITRE
2009-07-27	updated Maintenance_Notes, Relationships
2009-03-10	CWE Content Team	MITRE
2009-03-10	updated Potential_Mitigations
2009-01-12	CWE Content Team	MITRE
2009-01-12	updated Demonstrative_Examples, Description, Observed_Examples, Potential_Mitigations, References, Relationships
2008-09-08	CWE Content Team	MITRE
2008-09-08	updated Background_Details, Common_Consequences, Description, Relationships, Taxonomy_Mappings
2008-08-15		Veracode
2008-08-15	Suggested OWASP Top Ten 2004 mapping
Previous Entry Names
Change Date	Previous Entry Name
2008-04-11	Using a Broken or Risky Cryptographic Algorithm

Weakness ID: 134

View customized information:

Description

The product uses a function that accepts a format string as an argument, but the format string originates from an external source.

Common Consequences

Impact	Details
Read Memory	Scope: Confidentiality Format string problems allow for information disclosure which can severely simplify exploitation of the program.
Modify Memory; Execute Unauthorized Code or Commands	Scope: Integrity, Confidentiality, Availability Format string problems can result in the execution of arbitrary code, buffer overflows, denial of service, or incorrect data representation.

Potential Mitigations

Phase(s)	Mitigation
Requirements	Choose a language that is not subject to this flaw.
Implementation	Ensure that all format string functions are passed a static string which cannot be controlled by the user, and that the proper number of arguments are always sent to that function as well. If at all possible, use functions that do not support the %n operator in format strings. [REF-116] [REF-117]
Build and Compilation	Run compilers and linkers with high warning levels, since they may detect incorrect usage.

Relationships

Relevant to the view "Research Concepts" (View-1000)

Nature	Type	ID	Name
ChildOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	668	Exposure of Resource to Wrong Sphere
CanPrecede	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	123	Write-what-where Condition

Relevant to the view "Software Development" (View-699)

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	133	String Errors

Relevant to the view "Weaknesses for Simplified Mapping of Published Vulnerabilities" (View-1003)

Nature	Type	ID	Name
ChildOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	668	Exposure of Resource to Wrong Sphere

Relevant to the view "Seven Pernicious Kingdoms" (View-700)

Nature	Type	ID	Name
ChildOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	20	Improper Input Validation

Modes Of Introduction

Phase	Note
Implementation	The programmer rarely intends for a format string to be externally-controlled at all. This weakness is frequently introduced in code that constructs log messages, where a constant format string is omitted.
Implementation	In cases such as localization and internationalization, the language-specific message repositories could be an avenue for exploitation, but the format string issue would be resultant, since attacker control of those repositories would also allow modification of message length, format, and content.

Applicable Platforms

Languages

C (Often Prevalent)

C++ (Often Prevalent)

Perl (Rarely Prevalent)

Likelihood Of Exploit

High

Demonstrative Examples

Example 1

The following program prints a string provided as an argument.

(bad code)

Example Language: C

#include <stdio.h>

void printWrapper(char *string) {

printf(string);

}

int main(int argc, char **argv) {

char buf[5012];
memcpy(buf, argv[1], 5012);
printWrapper(argv[1]);
return (0);

}

The example is exploitable, because of the call to printf() in the printWrapper() function. Note: The stack buffer was added to make exploitation more simple.

Example 2

The following code copies a command line argument into a buffer using snprintf().

(bad code)

Example Language: C

int main(int argc, char **argv){

char buf[128];
...
snprintf(buf,128,argv[1]);

}

This code allows an attacker to view the contents of the stack and write to the stack using a command line argument containing a sequence of formatting directives. The attacker can read from the stack by providing more formatting directives, such as %x, than the function takes as arguments to be formatted. (In this example, the function takes no arguments to be formatted.) By using the %n formatting directive, the attacker can write to the stack, causing snprintf() to write the number of bytes output thus far to the specified argument (rather than reading a value from the argument, which is the intended behavior). A sophisticated version of this attack will use four staggered writes to completely control the value of a pointer on the stack.

Example 3

Certain implementations make more advanced attacks even easier by providing format directives that control the location in memory to read from or write to. An example of these directives is shown in the following code, written for glibc:

(bad code)

Example Language: C

printf("%d %d %1$d %1$d\n", 5, 9);

This code produces the following output: 5 9 5 5 It is also possible to use half-writes (%hn) to accurately control arbitrary DWORDS in memory, which greatly reduces the complexity needed to execute an attack that would otherwise require four staggered writes, such as the one mentioned in a separate example.

Selected Observed Examples

Reference	Description
CVE-2002-1825	format string in Perl program
CVE-2001-0717	format string in bad call to syslog function
CVE-2002-0573	format string in bad call to syslog function
CVE-2002-1788	format strings in NNTP server responses
CVE-2006-2480	Format string vulnerability exploited by triggering errors or warnings, as demonstrated via format string specifiers in a .bmp filename.
CVE-2007-2027	Chain: untrusted search path enabling resultant format string by loading malicious internationalization messages

Weakness Ordinalities

Ordinality	Description
Primary	(where the weakness exists independent of other weaknesses)

Detection Methods

Method	Details
Automated Static Analysis	This weakness can often be detected using automated static analysis tools. Many modern tools use data flow analysis or constraint-based techniques to minimize the number of false positives.
Black Box	Since format strings often occur in rarely-occurring erroneous conditions (e.g. for error message logging), they can be difficult to detect using black box methods. It is highly likely that many latent issues exist in executables that do not have associated source code (or equivalent source. Effectiveness: Limited
Automated Static Analysis - Binary or Bytecode	According to SOAR, the following detection techniques may be useful: Highly cost effective: Bytecode Weakness Analysis - including disassembler + source code weakness analysis Binary Weakness Analysis - including disassembler + source code weakness analysis Cost effective for partial coverage: Binary / Bytecode simple extractor - strings, ELF readers, etc. Effectiveness: High
Manual Static Analysis - Binary or Bytecode	According to SOAR, the following detection techniques may be useful: Cost effective for partial coverage: Binary / Bytecode disassembler - then use manual analysis for vulnerabilities & anomalies Effectiveness: SOAR Partial
Dynamic Analysis with Automated Results Interpretation	According to SOAR, the following detection techniques may be useful: Cost effective for partial coverage: Web Application Scanner Web Services Scanner Database Scanners Effectiveness: SOAR Partial
Dynamic Analysis with Manual Results Interpretation	According to SOAR, the following detection techniques may be useful: Cost effective for partial coverage: Fuzz Tester Framework-based Fuzzer Effectiveness: SOAR Partial
Manual Static Analysis - Source Code	According to SOAR, the following detection techniques may be useful: Highly cost effective: Manual Source Code Review (not inspections) Cost effective for partial coverage: Focused Manual Spotcheck - Focused manual analysis of source Effectiveness: High
Automated Static Analysis - Source Code	According to SOAR, the following detection techniques may be useful: Highly cost effective: Source code Weakness Analyzer Context-configured Source Code Weakness Analyzer Cost effective for partial coverage: Warning Flags Effectiveness: High
Architecture or Design Review	According to SOAR, the following detection techniques may be useful: Highly cost effective: Formal Methods / Correct-By-Construction Cost effective for partial coverage: Inspection (IEEE 1028 standard) (can apply to requirements, design, source code, etc.) Effectiveness: High

Functional Areas

Logging
Error Handling
String Processing

Affected Resources

Memory

Memberships

Nature	Type	ID	Name
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	635	Weaknesses Originally Used by NVD from 2008 to 2016
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	726	OWASP Top Ten 2004 Category A5 - Buffer Overflows
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	743	CERT C Secure Coding Standard (2008) Chapter 10 - Input Output (FIO)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	808	2010 Top 25 - Weaknesses On the Cusp
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	845	The CERT Oracle Secure Coding Standard for Java (2011) Chapter 2 - Input Validation and Data Sanitization (IDS)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	865	2011 Top 25 - Risky Resource Management
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	877	CERT C++ Secure Coding Section 09 - Input Output (FIO)
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	884	CWE Cross-section
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	990	SFP Secondary Cluster: Tainted Input to Command
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1131	CISQ Quality Measures (2016) - Security
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1134	SEI CERT Oracle Secure Coding Standard for Java - Guidelines 00. Input Validation and Data Sanitization (IDS)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1163	SEI CERT C Coding Standard - Guidelines 09. Input Output (FIO)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1179	SEI CERT Perl Coding Standard - Guidelines 01. Input Validation and Data Sanitization (IDS)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1308	CISQ Quality Measures - Security
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1340	CISQ Data Protection Measures
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1399	Comprehensive Categorization: Memory Safety

Vulnerability Mapping Notes

Usage	ALLOWED (this CWE ID may be used to map to real-world vulnerabilities)
Reason	Acceptable-Use
Rationale	This CWE entry is at the Base level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.
Comments	Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction.

Notes

Applicable Platform

This weakness is possible in any programming language that support format strings.

Research Gap

Format string issues are under-studied for languages other than C. Memory or disk consumption, control flow or variable alteration, and data corruption may result from format string exploitation in applications written in other languages such as Perl, PHP, Python, etc.

Other

In some circumstances, such as internationalization, the set of format strings is externally controlled by design. If the source of these format strings is trusted (e.g. only contained in library files that are only modifiable by the system administrator), then the external control might not itself pose a vulnerability.

While Format String vulnerabilities typically fall under the Buffer Overflow category, technically they are not overflowed buffers. The Format String vulnerability is fairly new (circa 1999) and stems from the fact that there is no realistic way for a function that takes a variable number of arguments to determine just how many arguments were passed in. The most common functions that take a variable number of arguments, including C-runtime functions, are the printf() family of calls. The Format String problem appears in a number of ways. A *printf() call without a format specifier is dangerous and can be exploited. For example, printf(input); is exploitable, while printf(y, input); is not exploitable in that context. The result of the first call, used incorrectly, allows for an attacker to be able to peek at stack memory since the input string will be used as the format specifier. The attacker can stuff the input string with format specifiers and begin reading stack values, since the remaining parameters will be pulled from the stack. Worst case, this improper use may give away enough control to allow an arbitrary value (or values in the case of an exploit program) to be written into the memory of the running program.

Frequently targeted entities are file names, process names, identifiers.

Format string problems are a classic C/C++ issue that are now rare due to the ease of discovery. One main reason format string vulnerabilities can be exploited is due to the %n operator. The %n operator will write the number of characters, which have been printed by the format string therefore far, to the memory pointed to by its argument. Through skilled creation of a format string, a malicious user may use values on the stack to create a write-what-where condition. Once this is achieved, they can execute arbitrary code. Other operators can be used as well; for example, a %9999s operator could also trigger a buffer overflow, or when used in file-formatting functions like fprintf, it can generate a much larger output than intended.

Taxonomy Mappings

Mapped Taxonomy Name	Node ID	Fit	Mapped Node Name
PLOVER			Format string vulnerability
7 Pernicious Kingdoms			Format String
CLASP			Format string problem
CERT C Secure Coding	FIO30-C	Exact	Exclude user input from format strings
CERT C Secure Coding	FIO47-C	CWE More Specific	Use valid format strings
OWASP Top Ten 2004	A1	CWE More Specific	Unvalidated Input
WASC	6		Format String
The CERT Oracle Secure Coding Standard for Java (2011)	IDS06-J		Exclude user input from format strings
SEI CERT Perl Coding Standard	IDS30-PL	Exact	Exclude user input from format strings
Software Fault Patterns	SFP24		Tainted input to command
OMG ASCSM	ASCSM-CWE-134

Related Attack Patterns

CAPEC-ID	Attack Pattern Name
CAPEC-135	Format String Injection
CAPEC-67	String Format Overflow in syslog()

References

[REF-116]	Steve Christey. "Format String Vulnerabilities in Perl Programs". <https://seclists.org/fulldisclosure/2005/Dec/91>. (URL validated: 2023-04-07)
[REF-117]	Hal Burch and Robert C. Seacord. "Programming Language Format String Vulnerabilities". <https://drdobbs.com/security/programming-language-format-string-vulne/197002914>. (URL validated: 2023-04-07)
[REF-118]	Tim Newsham. "Format String Attacks". Guardent. 2000-09-09. <http://www.thenewsh.com/~newsham/format-string-attacks.pdf>.
[REF-7]	Michael Howard and David LeBlanc. "Writing Secure Code". Chapter 5, "Format String Bugs" Page 147. 2nd Edition. Microsoft Press. 2002-12-04. <https://www.microsoftpressstore.com/store/writing-secure-code-9780735617223>.
[REF-44]	Michael Howard, David LeBlanc and John Viega. "24 Deadly Sins of Software Security". "Sin 6: Format String Problems." Page 109. McGraw-Hill. 2010.
[REF-62]	Mark Dowd, John McDonald and Justin Schuh. "The Art of Software Security Assessment". Chapter 8, "C Format Strings", Page 422. 1st Edition. Addison Wesley. 2006.
[REF-962]	Object Management Group (OMG). "Automated Source Code Security Measure (ASCSM)". ASCSM-CWE-134. 2016-01. <http://www.omg.org/spec/ASCSM/1.0/>.

Content History

Submissions
Submission Date	Submitter	Organization
2006-07-19 (CWE Draft 3, 2006-07-19)	PLOVER
2006-07-19 (CWE Draft 3, 2006-07-19)
Modifications
Modification Date	Modifier	Organization
2025-04-03 (CWE 4.17, 2025-04-03)	CWE Content Team	MITRE
2025-04-03 (CWE 4.17, 2025-04-03)	updated Common_Consequences, Demonstrative_Examples, Description, Diagram, Other_Notes
2023-06-29	CWE Content Team	MITRE
2023-06-29	updated Mapping_Notes
2023-04-27	CWE Content Team	MITRE
2023-04-27	updated References, Relationships
2023-01-31	CWE Content Team	MITRE
2023-01-31	updated Description
2021-03-15	CWE Content Team	MITRE
2021-03-15	updated Potential_Mitigations, Relationships
2020-12-10	CWE Content Team	MITRE
2020-12-10	updated Common_Consequences, Relationships
2020-08-20	CWE Content Team	MITRE
2020-08-20	updated Relationships
2020-02-24	CWE Content Team	MITRE
2020-02-24	updated Detection_Factors, Relationships
2019-09-19	CWE Content Team	MITRE
2019-09-19	updated Relationships
2019-06-20	CWE Content Team	MITRE
2019-06-20	updated Relationships
2019-01-03	CWE Content Team	MITRE
2019-01-03	updated References, Relationships, Taxonomy_Mappings
2018-03-27	CWE Content Team	MITRE
2018-03-27	updated References
2017-11-08	CWE Content Team	MITRE
2017-11-08	updated Applicable_Platforms, Causal_Nature, Functional_Areas, Likelihood_of_Exploit, Other_Notes, References, Relationships, Taxonomy_Mappings, White_Box_Definitions
2015-12-07	CWE Content Team	MITRE
2015-12-07	updated Description, Modes_of_Introduction, Name, Relationships
2014-07-30	CWE Content Team	MITRE
2014-07-30	updated Demonstrative_Examples, Detection_Factors, Relationships, Taxonomy_Mappings
2012-05-11	CWE Content Team	MITRE
2012-05-11	updated Observed_Examples, References, Related_Attack_Patterns, Relationships, Taxonomy_Mappings
2011-09-13	CWE Content Team	MITRE
2011-09-13	updated Potential_Mitigations, References, Relationships, Taxonomy_Mappings
2011-06-27	CWE Content Team	MITRE
2011-06-27	updated Modes_of_Introduction, Relationships
2011-06-01	CWE Content Team	MITRE
2011-06-01	updated Common_Consequences, Relationships, Taxonomy_Mappings
2010-02-16	CWE Content Team	MITRE
2010-02-16	updated Detection_Factors, References, Relationships, Taxonomy_Mappings
2009-07-27	CWE Content Team	MITRE
2009-07-27	updated White_Box_Definitions
2009-07-17	KDM Analytics
2009-07-17	Improved the White_Box_Definition
2009-05-27	CWE Content Team	MITRE
2009-05-27	updated Demonstrative_Examples
2009-03-10	CWE Content Team	MITRE
2009-03-10	updated Relationships
2008-11-24	CWE Content Team	MITRE
2008-11-24	updated Relationships, Taxonomy_Mappings
2008-09-08	CWE Content Team	MITRE
2008-09-08	updated Applicable_Platforms, Common_Consequences, Detection_Factors, Modes_of_Introduction, Relationships, Other_Notes, Research_Gaps, Taxonomy_Mappings, Weakness_Ordinalities
2008-08-01		KDM Analytics
2008-08-01	added/updated white box definitions
Previous Entry Names
Change Date	Previous Entry Name
2015-12-07	Uncontrolled Format String

Weakness ID: 330

View customized information:

Description

The product uses insufficiently random numbers or values in a security context that depends on unpredictable numbers.

Extended Description

When product generates predictable values in a context requiring unpredictability, it may be possible for an attacker to guess the next value that will be generated, and use this guess to impersonate another user or access sensitive information.

Common Consequences

Impact	Details
Other	Scope: Confidentiality, Other When a protection mechanism relies on random values to restrict access to a sensitive resource, such as a session ID or a seed for generating a cryptographic key, then the resource being protected could be accessed by guessing the ID or key.
Bypass Protection Mechanism; Other	Scope: Access Control, Other If product relies on unique, unguessable IDs to identify a resource, an attacker might be able to guess an ID for a resource that is owned by another user. The attacker could then read the resource, or pre-create a resource with the same ID to prevent the legitimate program from properly sending the resource to the intended user. For example, a product might maintain session information in a file whose name is based on a username. An attacker could pre-create this file for a victim user, then set the permissions so that the application cannot generate the session for the victim, preventing the victim from using the application.
Bypass Protection Mechanism; Gain Privileges or Assume Identity	Scope: Access Control When an authorization or authentication mechanism relies on random values to restrict access to restricted functionality, such as a session ID or a seed for generating a cryptographic key, then an attacker may access the restricted functionality by guessing the ID or key.

Potential Mitigations

Phase(s)	Mitigation
Architecture and Design	Use a well-vetted algorithm that is currently considered to be strong by experts in the field, and select well-tested implementations with adequate length seeds. In general, if a pseudo-random number generator is not advertised as being cryptographically secure, then it is probably a statistical PRNG and should not be used in security-sensitive contexts. Pseudo-random number generators can produce predictable numbers if the generator is known and the seed can be guessed. A 256-bit seed is a good starting point for producing a "random enough" number.
Implementation	Consider a PRNG that re-seeds itself as needed from high quality pseudo-random output sources, such as hardware devices.
Testing	Use automated static analysis tools that target this type of weakness. Many modern techniques use data flow analysis to minimize the number of false positives. This is not a perfect solution, since 100% accuracy and coverage are not feasible.
Architecture and Design; Requirements	Strategy: Libraries or Frameworks Use products or modules that conform to FIPS 140-2 [REF-267] to avoid obvious entropy problems. Consult FIPS 140-2 Annex C ("Approved Random Number Generators").
Testing	Use tools and techniques that require manual (human) analysis, such as penetration testing, threat modeling, and interactive tools that allow the tester to record and modify an active session. These may be more effective than strictly automated techniques. This is especially the case with weaknesses that are related to design and business rules.

Relationships

Relevant to the view "Research Concepts" (View-1000)

Nature	Type	ID	Name
ChildOf	Pillar - a weakness that is the most abstract type of weakness and represents a theme for all class/base/variant weaknesses related to it. A Pillar is different from a Category as a Pillar is still technically a type of weakness that describes a mistake, while a Category represents a common characteristic used to group related things.	693	Protection Mechanism Failure
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	331	Insufficient Entropy
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	334	Small Space of Random Values
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	335	Incorrect Usage of Seeds in Pseudo-Random Number Generator (PRNG)
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	338	Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG)
ParentOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	340	Generation of Predictable Numbers or Identifiers
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	344	Use of Invariant Value in Dynamically Changing Context
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	1204	Generation of Weak Initialization Vector (IV)
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	1241	Use of Predictable Algorithm in Random Number Generator
CanPrecede	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	804	Guessable CAPTCHA

Relevant to the view "Weaknesses for Simplified Mapping of Published Vulnerabilities" (View-1003)

Nature	Type	ID	Name
MemberOf	View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).	1003	Weaknesses for Simplified Mapping of Published Vulnerabilities
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	331	Insufficient Entropy
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	335	Incorrect Usage of Seeds in Pseudo-Random Number Generator (PRNG)
ParentOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	338	Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG)

Relevant to the view "Architectural Concepts" (View-1008)

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1013	Encrypt Data

Background Details

Computers are deterministic machines, and as such are unable to produce true randomness. Pseudo-Random Number Generators (PRNGs) approximate randomness algorithmically, starting with a seed from which subsequent values are calculated. There are two types of PRNGs: statistical and cryptographic. Statistical PRNGs provide useful statistical properties, but their output is highly predictable and forms an easy to reproduce numeric stream that is unsuitable for use in cases where security depends on generated values being unpredictable. Cryptographic PRNGs address this problem by generating output that is more difficult to predict. For a value to be cryptographically secure, it must be impossible or highly improbable for an attacker to distinguish between it and a truly random value.

Modes Of Introduction

Phase	Note
Architecture and Design
Implementation	REALIZATION: This weakness is caused during implementation of an architectural security tactic.

Applicable Platforms

Languages	Class: Not Language-Specific (Undetermined Prevalence)
Technologies	Class: Not Technology-Specific (Undetermined Prevalence)

Likelihood Of Exploit

High

Demonstrative Examples

Example 1

This code attempts to generate a unique random identifier for a user's session.

(bad code)

Example Language: PHP

function generateSessionID($userID){

srand($userID);
return rand();

}

Because the seed for the PRNG is always the user's ID, the session ID will always be the same. An attacker could thus predict any user's session ID and potentially hijack the session.

This example also exhibits a Small Seed Space (CWE-339).

Example 2

The following code uses a statistical PRNG to create a URL for a receipt that remains active for some period of time after a purchase.

(bad code)

Example Language: Java

String GenerateReceiptURL(String baseUrl) {

Random ranGen = new Random();
ranGen.setSeed((new Date()).getTime());
return(baseUrl + ranGen.nextInt(400000000) + ".html");

}

This code uses the Random.nextInt() function to generate "unique" identifiers for the receipt pages it generates. Because Random.nextInt() is a statistical PRNG, it is easy for an attacker to guess the strings it generates. Although the underlying design of the receipt system is also faulty, it would be more secure if it used a random number generator that did not produce predictable receipt identifiers, such as a cryptographic PRNG.

Selected Observed Examples

Reference	Description
CVE-2021-3692	PHP framework uses mt_rand() function (Marsenne Twister) when generating tokens
CVE-2020-7010	Cloud application on Kubernetes generates passwords using a weak random number generator based on deployment time.
CVE-2009-3278	Crypto product uses rand() library function to generate a recovery key, making it easier to conduct brute force attacks.
CVE-2009-3238	Random number generator can repeatedly generate the same value.
CVE-2009-2367	Web application generates predictable session IDs, allowing session hijacking.
CVE-2009-2158	Password recovery utility generates a relatively small number of random passwords, simplifying brute force attacks.
CVE-2009-0255	Cryptographic key created with a seed based on the system time.
CVE-2008-5162	Kernel function does not have a good entropy source just after boot.
CVE-2008-4905	Blogging software uses a hard-coded salt when calculating a password hash.
CVE-2008-4929	Bulletin board application uses insufficiently random names for uploaded files, allowing other users to access private files.
CVE-2008-3612	Handheld device uses predictable TCP sequence numbers, allowing spoofing or hijacking of TCP connections.
CVE-2008-2433	Web management console generates session IDs based on the login time, making it easier to conduct session hijacking.
CVE-2008-0166	SSL library uses a weak random number generator that only generates 65,536 unique keys.
CVE-2008-2108	Chain: insufficient precision causes extra zero bits to be assigned, reducing entropy for an API function that generates random numbers.
CVE-2008-2108	Chain: insufficient precision (CWE-1339) in random-number generator causes some zero bits to be reliably generated, reducing the amount of entropy (CWE-331)
CVE-2008-2020	CAPTCHA implementation does not produce enough different images, allowing bypass using a database of all possible checksums.
CVE-2008-0087	DNS client uses predictable DNS transaction IDs, allowing DNS spoofing.
CVE-2008-0141	Application generates passwords that are based on the time of day.

Weakness Ordinalities

Ordinality	Description
Primary	(where the weakness exists independent of other weaknesses)

Detection Methods

Method	Details
Black Box	Use monitoring tools that examine the software's process as it interacts with the operating system and the network. This technique is useful in cases when source code is unavailable, if the software was not developed by you, or if you want to verify that the build phase did not introduce any new weaknesses. Examples include debuggers that directly attach to the running process; system-call tracing utilities such as truss (Solaris) and strace (Linux); system activity monitors such as FileMon, RegMon, Process Monitor, and other Sysinternals utilities (Windows); and sniffers and protocol analyzers that monitor network traffic. Attach the monitor to the process and look for library functions that indicate when randomness is being used. Run the process multiple times to see if the seed changes. Look for accesses of devices or equivalent resources that are commonly used for strong (or weak) randomness, such as /dev/urandom on Linux. Look for library or system calls that access predictable information such as process IDs and system time.
Automated Static Analysis - Binary or Bytecode	According to SOAR, the following detection techniques may be useful: Cost effective for partial coverage: Bytecode Weakness Analysis - including disassembler + source code weakness analysis Binary Weakness Analysis - including disassembler + source code weakness analysis Effectiveness: SOAR Partial
Manual Static Analysis - Binary or Bytecode	According to SOAR, the following detection techniques may be useful: Cost effective for partial coverage: Binary / Bytecode disassembler - then use manual analysis for vulnerabilities & anomalies Effectiveness: SOAR Partial
Dynamic Analysis with Manual Results Interpretation	According to SOAR, the following detection techniques may be useful: Cost effective for partial coverage: Man-in-the-middle attack tool Effectiveness: SOAR Partial
Manual Static Analysis - Source Code	According to SOAR, the following detection techniques may be useful: Highly cost effective: Focused Manual Spotcheck - Focused manual analysis of source Manual Source Code Review (not inspections) Effectiveness: High
Automated Static Analysis - Source Code	According to SOAR, the following detection techniques may be useful: Cost effective for partial coverage: Source code Weakness Analyzer Context-configured Source Code Weakness Analyzer Effectiveness: SOAR Partial
Architecture or Design Review	According to SOAR, the following detection techniques may be useful: Highly cost effective: Inspection (IEEE 1028 standard) (can apply to requirements, design, source code, etc.) Effectiveness: High

Functional Areas

Cryptography
Authentication
Session Management

Memberships

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	254	7PK - Security Features
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	723	OWASP Top Ten 2004 Category A2 - Broken Access Control
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	747	CERT C Secure Coding Standard (2008) Chapter 14 - Miscellaneous (MSC)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	753	2009 Top 25 - Porous Defenses
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	808	2010 Top 25 - Weaknesses On the Cusp
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	861	The CERT Oracle Secure Coding Standard for Java (2011) Chapter 18 - Miscellaneous (MSC)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	867	2011 Top 25 - Weaknesses On the Cusp
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	883	CERT C++ Secure Coding Section 49 - Miscellaneous (MSC)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	905	SFP Primary Cluster: Predictability
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1152	SEI CERT Oracle Secure Coding Standard for Java - Guidelines 49. Miscellaneous (MSC)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1169	SEI CERT C Coding Standard - Guidelines 14. Concurrency (CON)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1170	SEI CERT C Coding Standard - Guidelines 48. Miscellaneous (MSC)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1346	OWASP Top Ten 2021 Category A02:2021 - Cryptographic Failures
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1366	ICS Communications: Frail Security in Protocols
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	1414	Comprehensive Categorization: Randomness

Vulnerability Mapping Notes

Usage	DISCOURAGED (this CWE ID should not be used to map to real-world vulnerabilities)
Reason	Abstraction
Rationale	This CWE entry is a level-1 Class (i.e., a child of a Pillar). It might have lower-level children that would be more appropriate
Comments	Examine children of this entry to see if there is a better fit

Notes

Relationship

This can be primary to many other weaknesses such as cryptographic errors, authentication errors, symlink following, information leaks, and others.

Maintenance

As of CWE 4.3, CWE-330 and its descendants are being investigated by the CWE crypto team to identify gaps related to randomness and unpredictability, as well as the relationships between randomness and cryptographic primitives. This "subtree analysis" might result in the addition or deprecation of existing entries; the reorganization of relationships in some views, e.g. the research view (CWE-1000); more consistent use of terminology; and/or significant modifications to related entries.

Maintenance

As of CWE 4.5, terminology related to randomness, entropy, and predictability can vary widely. Within the developer and other communities, "randomness" is used heavily. However, within cryptography, "entropy" is distinct, typically implied as a measurement. There are no commonly-used definitions, even within standards documents and cryptography papers. Future versions of CWE will attempt to define these terms and, if necessary, distinguish between them in ways that are appropriate for different communities but do not reduce the usability of CWE for mapping, understanding, or other scenarios.

Taxonomy Mappings

Mapped Taxonomy Name	Node ID	Fit	Mapped Node Name
PLOVER			Randomness and Predictability
7 Pernicious Kingdoms			Insecure Randomness
OWASP Top Ten 2004	A2	CWE More Specific	Broken Access Control
CERT C Secure Coding	CON33-C	Imprecise	Avoid race conditions when using library functions
CERT C Secure Coding	MSC30-C	CWE More Abstract	Do not use the rand() function for generating pseudorandom numbers
CERT C Secure Coding	MSC32-C	CWE More Abstract	Properly seed pseudorandom number generators
WASC	11		Brute Force
WASC	18		Credential/Session Prediction
The CERT Oracle Secure Coding Standard for Java (2011)	MSC02-J		Generate strong random numbers

Related Attack Patterns

CAPEC-ID	Attack Pattern Name
CAPEC-112	Brute Force
CAPEC-485	Signature Spoofing by Key Recreation
CAPEC-59	Session Credential Falsification through Prediction

References

[REF-267]	Information Technology Laboratory, National Institute of Standards and Technology. "SECURITY REQUIREMENTS FOR CRYPTOGRAPHIC MODULES". 2001-05-25. <https://csrc.nist.gov/csrc/media/publications/fips/140/2/final/documents/fips1402.pdf>. (URL validated: 2023-04-07)
[REF-207]	John Viega and Gary McGraw. "Building Secure Software: How to Avoid Security Problems the Right Way". 1st Edition. Addison-Wesley. 2002.
[REF-7]	Michael Howard and David LeBlanc. "Writing Secure Code". Chapter 8, "Using Poor Random Numbers" Page 259. 2nd Edition. Microsoft Press. 2002-12-04. <https://www.microsoftpressstore.com/store/writing-secure-code-9780735617223>.
[REF-44]	Michael Howard, David LeBlanc and John Viega. "24 Deadly Sins of Software Security". "Sin 20: Weak Random Numbers." Page 299. McGraw-Hill. 2010.

Content History

Submissions
Submission Date	Submitter	Organization
2006-07-19 (CWE Draft 3, 2006-07-19)	PLOVER
2006-07-19 (CWE Draft 3, 2006-07-19)
Modifications
Modification Date	Modifier	Organization
2024-02-29 (CWE 4.14, 2024-02-29)	CWE Content Team	MITRE
2024-02-29 (CWE 4.14, 2024-02-29)	updated Mapping_Notes
2023-10-26	CWE Content Team	MITRE
2023-10-26	updated Observed_Examples
2023-06-29	CWE Content Team	MITRE
2023-06-29	updated Mapping_Notes, Relationships
2023-04-27	CWE Content Team	MITRE
2023-04-27	updated References, Relationships
2023-01-31	CWE Content Team	MITRE
2023-01-31	updated Common_Consequences, Description
2022-10-13	CWE Content Team	MITRE
2022-10-13	updated Observed_Examples, Relationships
2021-10-28	CWE Content Team	MITRE
2021-10-28	updated Relationships
2021-07-20	CWE Content Team	MITRE
2021-07-20	updated Demonstrative_Examples, Maintenance_Notes, Observed_Examples
2021-03-15	CWE Content Team	MITRE
2021-03-15	updated Maintenance_Notes, Relationships
2020-02-24	CWE Content Team	MITRE
2020-02-24	updated Applicable_Platforms, Description, Relationships
2019-06-20	CWE Content Team	MITRE
2019-06-20	updated Relationships
2019-01-03	CWE Content Team	MITRE
2019-01-03	updated Relationships, Taxonomy_Mappings
2018-03-27	CWE Content Team	MITRE
2018-03-27	updated References
2017-11-08	CWE Content Team	MITRE
2017-11-08	updated Functional_Areas, Likelihood_of_Exploit, Modes_of_Introduction, References, Relationships, Taxonomy_Mappings
2015-12-07	CWE Content Team	MITRE
2015-12-07	updated Relationships
2014-07-30	CWE Content Team	MITRE
2014-07-30	updated Detection_Factors
2014-06-23	CWE Content Team	MITRE
2014-06-23	updated Related_Attack_Patterns
2014-02-18	CWE Content Team	MITRE
2014-02-18	updated Related_Attack_Patterns
2012-05-11	CWE Content Team	MITRE
2012-05-11	updated Demonstrative_Examples, Observed_Examples, References, Relationships
2011-09-13	CWE Content Team	MITRE
2011-09-13	updated Potential_Mitigations, References, Relationships, Taxonomy_Mappings
2011-06-27	CWE Content Team	MITRE
2011-06-27	updated Relationships
2011-06-01	CWE Content Team	MITRE
2011-06-01	updated Common_Consequences, Relationships, Taxonomy_Mappings
2011-03-29	CWE Content Team	MITRE
2011-03-29	updated Demonstrative_Examples
2010-06-21	CWE Content Team	MITRE
2010-06-21	updated Detection_Factors, Potential_Mitigations
2010-04-05	CWE Content Team	MITRE
2010-04-05	updated Related_Attack_Patterns
2010-02-16	CWE Content Team	MITRE
2010-02-16	updated References, Relationships, Taxonomy_Mappings
2009-12-28	CWE Content Team	MITRE
2009-12-28	updated Applicable_Platforms, Common_Consequences, Description, Observed_Examples, Potential_Mitigations, Time_of_Introduction
2009-05-27	CWE Content Team	MITRE
2009-05-27	updated Demonstrative_Examples, Related_Attack_Patterns
2009-03-10	CWE Content Team	MITRE
2009-03-10	updated Potential_Mitigations
2009-01-12	CWE Content Team	MITRE
2009-01-12	updated Description, Likelihood_of_Exploit, Other_Notes, Potential_Mitigations, Relationships
2008-11-24	CWE Content Team	MITRE
2008-11-24	updated Relationships, Taxonomy_Mappings
2008-09-08	CWE Content Team	MITRE
2008-09-08	updated Background_Details, Relationships, Other_Notes, Relationship_Notes, Taxonomy_Mappings, Weakness_Ordinalities
2008-07-01	Eric Dalci	Cigital
2008-07-01	updated Time_of_Introduction
Previous Entry Names
Change Date	Previous Entry Name
2008-04-11	Randomness and Predictability

Common Weakness Enumeration

CWE VIEW: Weaknesses Addressed by the SEI CERT C++ Coding Standard (2016 Version)

View Components

CWE-464: Addition of Data Structure Sentinel

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CWE-770: Allocation of Resources Without Limits or Throttling

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CWE-587: Assignment of a Fixed Address to a Pointer

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CWE-563: Assignment to Variable without Use

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CWE-805: Buffer Access with Incorrect Length Value

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CWE-120: Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')

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CWE CATEGORY: CERT C++ Secure Coding Section 01 - Preprocessor (PRE)

CWE CATEGORY: CERT C++ Secure Coding Section 02 - Declarations and Initialization (DCL)

CWE CATEGORY: CERT C++ Secure Coding Section 03 - Expressions (EXP)

CWE CATEGORY: CERT C++ Secure Coding Section 04 - Integers (INT)

CWE CATEGORY: CERT C++ Secure Coding Section 05 - Floating Point Arithmetic (FLP)

CWE CATEGORY: CERT C++ Secure Coding Section 06 - Arrays and the STL (ARR)

CWE CATEGORY: CERT C++ Secure Coding Section 07 - Characters and Strings (STR)

CWE CATEGORY: CERT C++ Secure Coding Section 08 - Memory Management (MEM)

CWE CATEGORY: CERT C++ Secure Coding Section 09 - Input Output (FIO)

CWE CATEGORY: CERT C++ Secure Coding Section 10 - Environment (ENV)

CWE CATEGORY: CERT C++ Secure Coding Section 11 - Signals (SIG)

CWE CATEGORY: CERT C++ Secure Coding Section 12 - Exceptions and Error Handling (ERR)

CWE CATEGORY: CERT C++ Secure Coding Section 13 - Object Oriented Programming (OOP)

CWE CATEGORY: CERT C++ Secure Coding Section 14 - Concurrency (CON)

CWE CATEGORY: CERT C++ Secure Coding Section 49 - Miscellaneous (MSC)

CWE-482: Comparing instead of Assigning

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CWE-14: Compiler Removal of Code to Clear Buffers

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CWE-362: Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

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CWE-379: Creation of Temporary File in Directory with Insecure Permissions

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CWE-561: Dead Code

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CWE-390: Detection of Error Condition Without Action

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CWE-369: Divide By Zero

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CWE-415: Double Free

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CWE-462: Duplicate Key in Associative List (Alist)

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CWE-528: Exposure of Core Dump File to an Unauthorized Control Sphere

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CWE-488: Exposure of Data Element to Wrong Session

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CWE-403: Exposure of File Descriptor to Unintended Control Sphere ('File Descriptor Leak')

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CWE-497: Exposure of Sensitive System Information to an Unauthorized Control Sphere

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CWE-570: Expression is Always False

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CWE-571: Expression is Always True

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CWE-73: External Control of File Name or Path

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CWE-552: Files or Directories Accessible to External Parties

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CWE-590: Free of Memory not on the Heap

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CWE-686: Function Call With Incorrect Argument Type

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CWE-687: Function Call With Incorrectly Specified Argument Value

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CWE-209: Generation of Error Message Containing Sensitive Information

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CWE-754: Improper Check for Unusual or Exceptional Conditions

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CWE-703: Improper Check or Handling of Exceptional Conditions

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CWE-460: Improper Cleanup on Thrown Exception

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CWE-244: Improper Clearing of Heap Memory Before Release ('Heap Inspection')

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