{"id":"BIT-pillow-2026-96639","summary":"Pillow multi-frame loaders can reuse stale native image storage after mode transitions","details":"Pillow is a Python imaging library. From 11.0.0 until 13.0.0, multi-frame loaders can retain an ImagingCore allocation created for a narrow frame mode while a later frame of the same dimensions changes the logical mode and decoder tiles to wider RGB or CMYK data. ImageFile.load_prepare() reuses the stale native storage because _im is non-null without verifying that its mode and size still match. Crafted PSD, MPO, DCX, or MIC frame transitions can then write wider pixels into the narrow allocation, causing native out-of-bounds writes and crashes. The MPO path can also cause a native over-read and, in demonstrated runtime-specific profiles, command execution. This issue is fixed in version 13.0.0.","aliases":["CVE-2026-96639","GHSA-v9pv-5gc8-w2m6","PYSEC-2026-4339"],"modified":"2026-10-29T10:55:37.663049285Z","published":"2026-10-29T08:58:14.316Z","database_specific":{"severity":"Critical","cpes":["cpe:2.3:a:python:pillow:*:*:*:*:*:python:*:*"]},"references":[{"type":"FIX","url":"https://github.com/python-pillow/Pillow/commit/78d97d994579aef81aafe123773d525f40f2522a"},{"type":"REPORT","url":"https://github.com/python-pillow/Pillow/pull/10105"},{"type":"ARTICLE","url":"https://github.com/python-pillow/Pillow/releases/tag/13.0.0"},{"type":"ADVISORY","url":"https://github.com/python-pillow/Pillow/security/advisories/GHSA-v9pv-5gc8-w2m6"},{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-96639"}],"affected":[{"package":{"name":"pillow","ecosystem":"Bitnami","purl":"pkg:bitnami/pillow"},"ranges":[{"type":"SEMVER","events":[{"introduced":"11.0.0"},{"fixed":"13.0.0"}]}],"database_specific":{"source":"https://github.com/bitnami/vulndb/tree/main/data/pillow/BIT-pillow-2026-96639.json"},"severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"}]}],"schema_version":"1.9.2"}