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CVE-2026-87910

tarfile hardlink fallback ignores custom extraction filter rejection via None

MEDIUM
5.7
CVSS Score
Published: September 11, 2026 at 05:27 PM UTC
Updated: October 22, 2026 at 01:16 AM UTC
1 product affected across 1 vendorPython

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Severity
MEDIUM5.7
Exploit prediction
EPSS 0.6%
SSVC
No known exploit

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Python· Python
90%
03.11.03.12.03.13.03.14.03.15.0a1
Affected range stops below 3.10.22, so it looks safe — our inference, not a vendor statement
Affected range stops below 3.11.17, so it looks safe — our inference, not a vendor statement
Affected range stops below 3.12.15, so it looks safe — our inference, not a vendor statement
Affected range stops below 3.13.16, so it looks safe — our inference, not a vendor statement
Affected range stops below 3.15.0rc3, so it looks safe — our inference, not a vendor statement

References (12)

Vendor Advisory
Source: cverecord
https://mail.python.org/archives/list/[email protected]/thread/57TBTLL2W6APMZR3A25B2YV7GL3EPTDJ/
Patch
Source: cverecord
https://github.com/python/cpython/pull/157266
Issue Tracking
Source: cverecord
https://github.com/python/cpython/issues/157265
Source: af854a3a-2127-422b-91ae-364da2661108
http://www.openwall.com/lists/oss-security/2026/09/11/8
Patch
Source: cverecord
https://github.com/python/cpython/commit/d9565e54b1fc6d63c5be9afd58114499128fa57b
Patch
Source: cverecord
https://github.com/python/cpython/commit/fb2f0bbc3b35264f09cc2cb2934b7987527a6bc2
Patch
Source: cverecord
https://github.com/python/cpython/commit/9c17bace90f88dfba6d0e2fe23c8e7ae35f83955
Patch
Source: cverecord
https://github.com/python/cpython/commit/764fd0af8d9e19d3684a58d2e58bf770f0605036

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

5.7MEDIUMPSF
Vector?

Quick Info

StatusAWAITING ANALYSIS
CWE
CWE-22CWE-59

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