PT-2026-51546 · Python · Cpython

Haruki Oyama + 2 · Published 2026-06-23 · Updated 2026-06-23 · CVE-2026-11940

NVD

CVSS v4.0

7.8

High

Base vector

AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

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.

Fix

Path traversal

Link Following

Weakness Enumeration

CWE-22

CWE-59

Related Identifiers

CVE-2026-11940

Affected Products

Cpython

References · 8

• https://github.com/python/cpython/commit/27dd970bf6b17ebca7c8ed486a40ab043ed7af8f · Patch
• https://github.com/python/cpython/commit/672825e2f36a57e173959b0d9d409d4560dab8df · Patch
• https://github.com/python/cpython/commit/79c06bd5c6afa3c440d50faf7ee1b147c8832b4c · Patch
• https://github.com/python/cpython/pull/151559 · Patch
• https://github.com/python/cpython/commit/771d12dda5140313db0ac550292987975651bbde · Patch
• https://mail.python.org/archives/list/[e-mail]/thread/LD6QIISNQFQYOIEPJNEUIPV7S3V76FZH · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2026-11940 · Security Note
• https://github.com/python/cpython/issues/151558 · Note