CVE-2026-11940

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.

Weakness classification

• CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
• CWE-59: Improper Link Resolution Before File Access ('Link Following')

Primary references

• cna@python.org
• cna@python.org
• cna@python.org
• cna@python.org
• cna@python.org
• cna@python.org
• cna@python.org
• cna@python.org
• cna@python.org
• cna@python.org