Common Weakness Enumeration

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CWE-767: Access to Critical Private Variable via Public Method

Weakness ID: 767
Abstraction: Variant
Structure: Simple
Status: Incomplete
Presentation Filter:
+ Description
The software defines a public method that reads or modifies a private variable.
+ Extended Description
If an attacker modifies the variable to contain unexpected values, this could violate assumptions from other parts of the code. Additionally, if an attacker can read the private variable, it may expose sensitive information or make it easier to launch further attacks.
+ Relationships

The table(s) below 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" (CWE-1000)
ChildOfClassClass668Exposure of Resource to Wrong Sphere
+ Relevant to the view "Development Concepts" (CWE-699)
MemberOfCategoryCategory265Privilege / Sandbox Issues
+ 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 software life cycle at which introduction may occur, while the Note provides a typical scenario related to introduction during the given phase.

Architecture and Design
+ Applicable Platforms
The listings below show 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.


C++ (Undetermined Prevalence)

C# (Undetermined Prevalence)

Java (Undetermined Prevalence)

+ Common Consequences

The table below 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.


Technical Impact: Modify Application Data; Other

+ Demonstrative Examples

Example 1

The following example declares a critical variable to be private, and then allows the variable to be modified by public methods.

(bad code)
Example Language: C++ 
private: float price;
public: void changePrice(float newPrice) {
price = newPrice;


Example 2

The following example could be used to implement a user forum where a single user (UID) can switch between multiple profiles (PID).

(bad code)
Example Language: Java 
public class Client {
private int UID;
public int PID;
private String userName;
public Client(String userName){
PID = getDefaultProfileID();
UID = mapUserNametoUID( userName );
this.userName = userName;

public void setPID(int ID) {



The programmer implemented setPID with the intention of modifying the PID variable, but due to a typo. accidentally specified the critical variable UID instead. If the program allows profile IDs to be between 1 and 10, but a UID of 1 means the user is treated as an admin, then a user could gain administrative privileges as a result of this typo.

+ Potential Mitigations

Phase: Implementation

Use class accessor and mutator methods appropriately. Perform validation when accepting data from a public method that is intended to modify a critical private variable. Also be sure that appropriate access controls are being applied when a public method interfaces with critical data.
+ 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.
MemberOfCategoryCategory963SFP Secondary Cluster: Exposed Data
+ Notes


This entry is closely associated with access control for public methods. If the public methods are restricted with proper access controls, then the information in the private variable will not be exposed to unexpected parties. There may be chaining or composite relationships between improper access controls and this weakness.
+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
CLASPFailure to protect stored data from modification
Software Fault PatternsSFP23Exposed Data
CERT Perl Secure CodingOOP31-PLImpreciseDo not access private variables or subroutines in other packages
+ Content History
Submission DateSubmitterOrganization
2009-03-03CWE Content TeamMITRE
Modification DateModifierOrganization
2011-06-01CWE Content TeamMITRE
updated Common_Consequences
2012-05-11CWE Content TeamMITRE
updated Relationships
2014-07-30CWE Content TeamMITRE
updated Relationships, Taxonomy_Mappings
2017-11-08CWE Content TeamMITRE
updated Likelihood_of_Exploit, Relationships, Taxonomy_Mappings

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Page Last Updated: January 18, 2018