CVE-2025-4138
Bypassing extraction filter to create symlinks to arbitrary targets outside extraction directory
- Published
- Jun 3, 2025
- Updated
- Jul 31, 2026
- Assigning CNA
- PSF
- Evidence observed
- Aug 8, 2026
Primary CVSS
nvd · CVSS 3.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:NLow · next 30 days
- Percentile
- 70.6%
- Model date
- Sep 21, 2026
EPSS is a statistical estimate, not a certainty or a measure of impact. Combine it with CVSS, KEV status, exposure and your environment.
Summary
Allows the extraction filter to be ignored, allowing symlink targets to point outside the destination directory, and the modification of some file metadata. You are affected by this vulnerability if using the tarfile module to extract untrusted tar archives using TarFile.extractall() or TarFile.extract() using the filter= parameter with a value of "data" or "tar". See the tarfile extraction filters documentation https://docs.python.org/3/library/tarfile.html#tarfile-extraction-filter for more information. Note that for Python 3.14 or later the default value of filter= changed from "no filtering" to `"data", so if you are relying on this new default behavior then your usage is also affected. Note that none of these vulnerabilities significantly affect the installation of source distributions which are tar archives as source distributions already allow arbitrary code execution during the build process. However when evaluating source distributions it's important to avoid installing source distributions with suspicious links.
Sources
5Python PoC for CVE-2025-4138, a path traversal in Python's tarfile module abusing symlink chains to bypass PATH_MAX for arbitrary file write
CVE-2025-4138 / CVE-2025-4517 — Python tarfile PATH_MAX Symlink Filter Bypass
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