What’s Vulnerable › Vulnerabilities

CVE-2026-11940: tarfile extraction filter bypass allows escaping the destination directory

• Severity: high (CVSS 7.8 v4.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.8% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-06-23 · updated 2026-10-26
• Weakness: CWE-22

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

• Python: before 3.10.21; from 3.11.0 before 3.11.16; from 3.12.0 before 3.12.14; from 3.13.0 before 3.13.15; from 3.14.0 before 3.14.7; from 3.15.0a1 before 3.15.0b4 — fixed in 3.10.21, 3.11.16, 3.12.14, 3.13.15, 3.14.7, 3.15.0b4

How to fix

Upgrade to a fixed version: Python 3.10.21, 3.11.16, 3.12.14, 3.13.15. Check the vendor advisory for mitigations.

References

• https://github.com/python/cpython/commit/0f852b3f07dd8e71e40326a51c02afbf16a42cc5
• https://github.com/python/cpython/commit/27dd970bf6b17ebca7c8ed486a40ab043ed7af8f
• https://github.com/python/cpython/commit/672825e2f36a57e173959b0d9d409d4560dab8df
• https://github.com/python/cpython/commit/771d12dda5140313db0ac550292987975651bbde
• https://github.com/python/cpython/commit/79c06bd5c6afa3c440d50faf7ee1b147c8832b4c
• https://github.com/python/cpython/commit/be13e86f6b9788a6f4d0419dffef72cbae5865c9
• https://github.com/python/cpython/commit/e5fdbd8d5aa923bd9111b112ea73bd6ec7c47877
• https://github.com/python/cpython/issues/151558
• https://github.com/python/cpython/pull/151559
• https://mail.python.org/archives/list/security-announce@python.org/thread/LD6QIISNQFQYOIEPJNEUIPV7S3V76FZH/

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