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Path TraversalWeakness · CWE-22

CVE-2026-11940

HIGH · 7.8 CVSS v4.0 Published 2026-06-23
Patch available
A vendor patch is available. No clean upgrade release — apply the published patch.
See remediation →
87/100
Remediation priority · High
Remotely reachable No privileges Zero-click Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis
How this class of weakness works · CWE-22

A file path is built from user input without being confined, so sequences like “../” let an attacker step outside the intended directory. That can expose configuration, credentials, or source code, and in the worst case lets an attacker write files where they shouldn't. A durable fix resolves and canonicalises the path, then rejects anything that escapes a known-safe base directory.

General guidance for the path traversal class — the official description and references above are authoritative for this specific CVE. Want a bespoke review and a reviewed fix? Ask our team →

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
Authentication
X
User interaction
None
Scope
X

CVSS:4.0/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

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Patch available Apply the vendor patch
Vendor patch github.com →
Recommended fix Moderate confidence

Python 3.13.x or latest stable Python 3.x release containing the commit 27dd970bf6b17ebca7c8ed486a40ab043ed7af8f

  1. 1. Identify the current Python version in use by running 'python3 --version' or 'python --version'.
  2. 2. Check if your current version is affected by reviewing the Python release notes for versions containing fixes for CVE-2025-4330 and CVE-2026-11940.
  3. 3. Download or install a Python version that includes the fix from the commit 27dd970bf6b17ebca7c8ed486a40ab043ed7af8f (typically Python 3.13.x or later patch releases).
  4. 4. If using a virtual environment, recreate it with the new Python version: 'python3 -m venv /path/to/new/venv'.
  5. 5. Reinstall project dependencies into the new environment.
  6. 6. Test that tarfile.extractall() with 'data' or 'tar' filters now correctly rejects malicious archives containing hardlinks to symlinks at deeper paths.
Caveat Minor - this is a security fix; Python minor version upgrades generally have minimal breaking changes for well-tested code

Generated from the published advisory — verify against the referenced sources before acting.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-11940 in production — separate from our analysis above.

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What this is

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