CVE-2025-6075

If the value passed to os.path.expandvars() is user-controlled a performance degradation is possible when expanding environment variables.

Weakness

The product does not properly control the allocation and maintenance of a limited resource.

Affected Software

Potential Mitigations

• Mitigation of resource exhaustion attacks requires that the target system either:

• The first of these solutions is an issue in itself though, since it may allow attackers to prevent the use of the system by a particular valid user. If the attacker impersonates the valid user, they may be able to prevent the user from accessing the server in question.

• The second solution is simply difficult to effectively institute – and even when properly done, it does not provide a full solution. It simply makes the attack require more resources on the part of the attacker.

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/147.html
• https://cwe.mitre.org/data/definitions/227.html
• https://cwe.mitre.org/data/definitions/492.html

References

• https://github.com/python/cpython/commit/2e6150adccaaf5bd95d4c19dfd04a36e0b325d8c
• https://github.com/python/cpython/commit/5dceb93486176e6b4a6d9754491005113eb23427
• https://github.com/python/cpython/commit/631ba3407e3348ccd56ce5160c4fb2c5dc5f4d84
• https://github.com/python/cpython/commit/892747b4cf0f95ba8beb51c0d0658bfaa381ebca
• https://github.com/python/cpython/commit/9ab89c026aa9611c4b0b67c288b8303a480fe742
• https://github.com/python/cpython/commit/c8a5f3435c342964e0a432cc9fb448b7dbecd1ba
• https://github.com/python/cpython/commit/f029e8db626ddc6e3a3beea4eff511a71aaceb5c
• https://github.com/python/cpython/issues/136065
• https://mail.python.org/archives/list/security-announce@python.org/thread/IUP5QJ6D4KK6ULHOMPC7DPNKRYQTQNLA/