CVE-2026-11940

NameCVE-2026-11940
Descriptiontarfile.extractall() with the 'data' or 'tar' filter could be bypassed by a crafted archive where a hardlink references a symlink stored at a deeper name than the hardlink itself.  The extraction fallback validated the symlink at it's archived location but recreated it at the hardlink's shallower path, letting a relative target the filter judged contained escape the destination directory.  This allowed a malicious tar archive to create a symlink pointing outside the destination, enabling out-of-destination file reads or writes. This was an incomplete fix of CVE-2025-4330.
SourceCVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
pypy3 (PTS)bullseye7.3.5+dfsg-2+deb11u2vulnerable
bullseye (security)7.3.5+dfsg-2+deb11u5vulnerable
bookworm7.3.11+dfsg-2+deb12u3vulnerable
trixie7.3.19+dfsg-2vulnerable
sid, forky7.3.23+dfsg-1vulnerable
python2.7 (PTS)bullseye2.7.18-8+deb11u1vulnerable
python3.11 (PTS)bookworm3.11.2-6+deb12u7vulnerable
bookworm (security)3.11.2-6+deb12u3vulnerable
python3.13 (PTS)trixie3.13.5-2+deb13u2vulnerable
sid, forky3.13.14-1vulnerable
python3.14 (PTS)sid, forky3.14.6-1vulnerable
python3.9 (PTS)bullseye3.9.2-1vulnerable
bullseye (security)3.9.2-1+deb11u7vulnerable

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
pypy3source(unstable)(unfixed)
python2.7source(unstable)(unfixed)
python3.11source(unstable)(unfixed)
python3.13source(unstable)(unfixed)
python3.14source(unstable)(unfixed)
python3.9source(unstable)(unfixed)

Notes

https://github.com/python/cpython/issues/151558
https://github.com/python/cpython/pull/151559
https://github.com/python/cpython/commit/672825e2f36a57e173959b0d9d409d4560dab8df (3.15 branch)
https://github.com/python/cpython/commit/79c06bd5c6afa3c440d50faf7ee1b147c8832b4c (3.14 branch)
https://github.com/python/cpython/commit/771d12dda5140313db0ac550292987975651bbde (3.13 branch)

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