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