What’s Vulnerable › Vulnerabilities

CVE-2025-8291: ZIP64 End of Central Directory (EOCD) Locator record offset not checked

• Severity: medium (CVSS 4.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2025-10-07 · updated 2026-10-08
• Weakness: CWE-1285

Description

The 'zipfile' module would not check the validity of the ZIP64 End of Central Directory (EOCD) Locator record offset value would not be used to locate the ZIP64 EOCD record, instead the ZIP64 EOCD record would be assumed to be the previous record in the ZIP archive. This could be abused to create ZIP archives that are handled differently by the 'zipfile' module compared to other ZIP implementations. Remediation maintains this behavior, but checks that the offset specified in the ZIP64 EOCD Locator record matches the expected value.

Affected products

• Python: before 3.9.24; from 3.10.0 before 3.10.19; from 3.11.0 before 3.11.14; from 3.12.0 before 3.12.12; from 3.13.0 before 3.13.10; from 3.14.0 before 3.14.1 — fixed in 3.10.19, 3.11.14, 3.12.12, 3.13.10, 3.14.1, 3.9.24

How to fix

Upgrade to a fixed version: Python 3.10.19, 3.11.14, 3.12.12, 3.13.10. Check the vendor advisory for mitigations.

References

• https://github.com/python/cpython/commit/162997bb70e067668c039700141770687bc8f267
• https://github.com/python/cpython/commit/1d29afb0d6218aa8fb5e1e4a6133a4778d89bb46
• https://github.com/python/cpython/commit/333d4a6f4967d3ace91492a39ededbcf3faa76a6
• https://github.com/python/cpython/commit/76437ac248ad8ca44e9bf697b02b1e2241df2196
• https://github.com/python/cpython/commit/8392b2f0d35678407d9ce7d95655a5b77de161b4
• https://github.com/python/cpython/commit/bca11ae7d575d87ed93f5dd6a313be6246e3e388
• https://github.com/python/cpython/commit/d11e69d6203080e3ec450446bfed0516727b85c3
• https://github.com/python/cpython/issues/139700
• https://github.com/python/cpython/pull/139702
• https://mail.python.org/archives/list/security-announce@python.org/thread/QECOPWMTH4VPPJAXAH2BGTA4XADOP62G/
• https://github.com/google/security-research/security/advisories/GHSA-hhv7-p4pg-wm6p
• https://github.com/psf/advisory-database/blob/main/advisories/python/PSF-2025-12.json

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