tarfile extraction filter bypass allows escaping the destination directory
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.
describes (1)
Related CVEs.
| ID | severity | exploitable | ||
|---|---|---|---|---|
| CVE-2026-11940US | — | — | ||
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… | ||||
references
External citations — patches, advisories, analysis.
- https://github.com/python/cpython/commit/0f852b3f07dd8e71e40326a51c02afbf16a42cc5WEB
- https://github.com/python/cpython/commit/27dd970bf6b17ebca7c8ed486a40ab043ed7af8fWEB
- https://github.com/python/cpython/commit/672825e2f36a57e173959b0d9d409d4560dab8dfWEB
- https://github.com/python/cpython/commit/771d12dda5140313db0ac550292987975651bbdeWEB
- https://github.com/python/cpython/commit/79c06bd5c6afa3c440d50faf7ee1b147c8832b4cWEB
- https://github.com/python/cpython/commit/be13e86f6b9788a6f4d0419dffef72cbae5865c9WEB
- https://github.com/python/cpython/commit/e5fdbd8d5aa923bd9111b112ea73bd6ec7c47877WEB
- https://github.com/python/cpython/issues/151558WEB
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