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
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.