CVE-2026-87910
Received Received - Intake

Path Traversal in Python tarfile Extraction

Vulnerability report for CVE-2026-87910, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.

Publication date: 2026-09-11

Last updated on: 2026-09-11

Assigner: Python Software Foundation

Description

When tarfile extracts a link on a system that doesn't support links, it falls back to extracting a member from the archive. In this case, the filter function is run twice: once for the extracted member, and once with name set to the location of the link. For one of the calls, the return value was ignored. Instead, the member should be skipped if either call returns None.

CVSS Scores

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Meta Information

Published
2026-09-11
Last Modified
2026-09-11
Generated
2026-09-11
AI Q&A
2026-09-11
EPSS Evaluated
N/A
NVD
EUVD

Affected Vendors & Products

Showing 7 associated CPEs
Vendor Product Version / Range
python cpython 3.10
python cpython 3.11
python cpython 3.12
python cpython 3.13
python cpython 3.14
python cpython 3.15
python cpython 3.16

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-22 The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.
CWE-59 The product attempts to access a file based on the filename, but it does not properly prevent that filename from identifying a link or shortcut that resolves to an unintended resource.

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Executive Summary

CVE-2026-87910 is a vulnerability in Python's tarfile module. When extracting a hardlink from a tar archive on a system that doesn't support hardlinks, the module falls back to extracting a regular file. During this process, a custom filter function is called twice: once for the extracted member and once for the link location. However, the return value of one call is ignored, which could allow unintended file extraction if the filter returns None.

Impact Analysis

This vulnerability could allow an attacker to bypass security filters and extract unintended files from a tar archive. This might lead to unauthorized file access, data leakage, or other malicious activities depending on the extracted files.

Mitigation Strategies

Update Python to a patched version (3.10 to 3.16) where the tarfile module fix has been applied. Check the linked CVE record or GitHub pull requests for specific patched versions.

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