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7.8 High

CVE-2026-11940 tarfile.extractall() with the 'data' or 'tar' filter could be bypassed by a crafted archive where a hardlink …

Description

tarfile.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.

Affected products and versions

Product Affected versions Fixed in
CPython 3.15 3.15.0a1 → < 3.15.0b4 3.15.0b4
CPython 3.14 3.14.0 → < 3.14.7 3.14.7
CPython 3.13 3.13.0 → < 3.13.15 3.13.15
CPython 3.12 3.12.0 → < 3.12.14 3.12.14
CPython 3.11 3.11.0 → < 3.11.16 3.11.16
CPython 3.10 earliest → < 3.10.21 3.10.21

References

Timeline

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