CWE-375

Base Abstraction Level
Pillar — Highest-level weakness category
Class — Abstract, language-independent
Base — Specific enough to detect
Variant — Tied to specific technology
Compound — Requires multiple weaknesses Draft MITRE CWE Status
Stable — Fully reviewed and complete
Draft — Under development, may change
Incomplete — Partially defined by MITRE
Deprecated — No longer recommended
Obsolete — Replaced by another CWE Exploit: Medium
Returning a Mutable Object to an Untrusted Caller

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.

Consequences

Access Control, Integrity — Modify Memory

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

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.