CVE-2025-4435

When using a TarFile.errorlevel = 0 and extracting with a filter the documented behavior is that any filtered members would be skipped and not extracted. However the actual behavior of TarFile.errorlevel = 0 in affected versions is that the member would still be extracted and not skipped.

Weakness

The product performs a calculation that generates incorrect or unintended results that are later used in security-critical decisions or resource management.

Potential Mitigations

• Use languages, libraries, or frameworks that make it easier to handle numbers without unexpected consequences.
• Examples include safe integer handling packages such as SafeInt (C++) or IntegerLib (C or C++).
• Use languages, libraries, or frameworks that make it easier to handle numbers without unexpected consequences.
• Examples include safe integer handling packages such as SafeInt (C++) or IntegerLib (C or C++).

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/128.html
• https://cwe.mitre.org/data/definitions/129.html

References

• https://github.com/python/cpython/commit/19de092debb3d7e832e5672cc2f7b788d35951da
• https://github.com/python/cpython/commit/28463dba112af719df1e8b0391c46787ad756dd9
• https://github.com/python/cpython/commit/3612d8f51741b11f36f8fb0494d79086bac9390a
• https://github.com/python/cpython/commit/4633f3f497b1ff70e4a35b6fe2c907cbe2d4cb2e
• https://github.com/python/cpython/commit/9c1110ef6652687d7c55f590f909720eddde965a
• https://github.com/python/cpython/commit/9e0ac76d96cf80b49055f6d6b9a6763fb9215c2a
• https://github.com/python/cpython/commit/aa9eb5f757ceff461e6e996f12c89e5d9b583b01
• https://github.com/python/cpython/commit/dd8f187d0746da151e0025c51680979ac5b4cfb1
• https://github.com/python/cpython/issues/135034
• https://github.com/python/cpython/pull/135037
• https://mail.python.org/archives/list/security-announce@python.org/thread/MAXIJJCUUMCL7ATZNDVEGGHUMQMUUKLG/