CVE-2025-8291: Python Software Foundation Cpython

Medium severity, CVSS 4.3. EPSS: 0.5% chance of exploitation in the next 30 days.

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 Software Foundation Cpython: before 3.9.24 (fixed in 3.9.24); from 3.10.0, before 3.10.19 (fixed in 3.10.19); from 3.11.0, before 3.11.14 (fixed in 3.11.14); from 3.12.0, before 3.12.12 (fixed in 3.12.12); from 3.13.0, before 3.13.10 (fixed in 3.13.10); from 3.14.0, before 3.14.1 (fixed in 3.14.1)

Published 2025-10-07. Last modified 2026-10-08.