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

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Description

Sending non-cloned mutable data as a return value may result in that data being altered or deleted by the calling function.

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.

Modes of Introduction:

– Implementation

 

Likelihood of Exploit: Medium

 

Related Weaknesses

CWE-668

 

Consequences

Access Control, Integrity: Modify Memory

Potentially data could be tampered with by another function which should not have been tampered with.

 

Potential Mitigations

Phase: Implementation

Description: 

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

Phase: Implementation

Description: 

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.

CVE References