Common Weakness Enumeration

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CWE-375: Returning a Mutable Object to an Untrusted Caller

Weakness ID: 375
Abstraction: Base
Structure: Simple
Status: Draft
Presentation Filter:
+ Description
Sending non-cloned mutable data as a return value may result in that data being altered or deleted by the calling function.
+ Extended Description
In situations where functions return references to mutable data, it is possible that the external code which called the function may make changes to the data sent. If this data was not previously cloned, the class will then be using modified data which may violate assumptions about its internal state.
+ 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)
MemberOfCategoryCategory371State 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.

+ 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)

C# (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.

Access Control

Technical Impact: Modify Memory

Potentially data could be tampered with by another function which should not have been tampered with.
+ Likelihood Of Exploit
+ Demonstrative Examples

Example 1

This class has a private list of patients, but provides a way to see the list :

(bad code)
Example Language: Java 
public class ClinicalTrial {
private PatientClass[] patientList = new PatientClass[50];
public getPatients(...){
return patientList;



While this code only means to allow reading of the patient list, the getPatients() method returns a reference to the class's original patient list instead of a reference to a copy of the list. Any caller of this method can arbitrarily modify the contents of the patient list even though it is a private member of the class.

+ Potential Mitigations

Phase: Implementation

Declare returned data which should not be altered as constant or immutable.

Phase: Implementation

Clone all mutable data before returning references to it. This is the preferred mitigation. This way, regardless of what changes are made to the data, a valid copy is retained for use by the class.
+ 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.
+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
CLASPMutable object returned
CERT Java Secure CodingOBJ04-JProvide mutable classes with copy functionality to safely allow passing instances to untrusted code
CERT Java Secure CodingOBJ05-JDefensively copy private mutable class members before returning their references
CERT Perl Secure CodingEXP34-PLImpreciseDo not modify $_ in list or sorting functions
Software Fault PatternsSFP23Exposed Data
+ Content History
Submission DateSubmitterOrganization
Modification DateModifierOrganization
2008-07-01Eric DalciCigital
updated Time_of_Introduction
2008-09-08CWE Content TeamMITRE
updated Applicable_Platforms, Common_Consequences, Relationships, Other_Notes, Taxonomy_Mappings
2010-09-27CWE Content TeamMITRE
updated Name, Taxonomy_Mappings
2011-06-01CWE Content TeamMITRE
updated Common_Consequences, Relationships, Taxonomy_Mappings
2012-05-11CWE Content TeamMITRE
updated Relationships, Taxonomy_Mappings
2012-10-30CWE Content TeamMITRE
updated Demonstrative_Examples
2014-06-23CWE Content TeamMITRE
updated Description, Other_Notes, Potential_Mitigations
2014-07-30CWE Content TeamMITRE
updated Relationships, Taxonomy_Mappings
2017-11-08CWE Content TeamMITRE
updated Taxonomy_Mappings
Previous Entry Names
Change DatePrevious Entry Name
2010-09-27Passing Mutable Objects to an Untrusted Method

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Page Last Updated: January 18, 2018