CVE-2025-4138Bypassing extraction filter to create symlinks to arbitrary targets outside extraction directory

Official description

Allows the extraction filter to be ignored, allowing symlink targets to point outside the destination directory, and the modification of some file metadata. You are affected by this vulnerability if using the tarfile module to extract untrusted tar archives using TarFile.extractall() or TarFile.extract() using the filter= parameter with a value of "data" or "tar". See the tarfile extraction filters documentation https://docs.python.org/3/library/tarfile.html#tarfile-extraction-filter  for more information. Note that for Python 3.14 or later the default value of filter= changed from "no filtering" to `"data", so if you are relying on this new default behavior then your usage is also affected. Note that none of these vulnerabilities significantly affect the installation of source distributions which are tar archives as source distributions already allow arbitrary code execution during the build process. However when evaluating source distributions it's important to avoid installing source distributions with suspicious links.

Affected packages & fixed versions

Affected products (as reported)

References

• https://github.com/python/cpython/issues/135034 issue-tracking
• https://github.com/python/cpython/pull/135037 patch
• https://mail.python.org/archives/list/security-announce@python.org/thread/MAXIJJCUUMCL7ATZNDVEGGHUMQMUUKLG/ vendor-advisory
• https://github.com/python/cpython/commit/3612d8f51741b11f36f8fb0494d79086bac9390a patch
• https://github.com/python/cpython/commit/9e0ac76d96cf80b49055f6d6b9a6763fb9215c2a patch
• https://gist.github.com/sethmlarson/52398e33eff261329a0180ac1d54f42f mitigation
• https://github.com/python/cpython/commit/19de092debb3d7e832e5672cc2f7b788d35951da patch
• https://github.com/python/cpython/commit/aa9eb5f757ceff461e6e996f12c89e5d9b583b01 patch
• https://github.com/python/cpython/commit/28463dba112af719df1e8b0391c46787ad756dd9 patch
• https://github.com/python/cpython/commit/4633f3f497b1ff70e4a35b6fe2c907cbe2d4cb2e patch
• https://github.com/python/cpython/commit/9c1110ef6652687d7c55f590f909720eddde965a patch
• https://github.com/python/cpython/commit/dd8f187d0746da151e0025c51680979ac5b4cfb1 patch