Pillow multi-frame loaders can reuse stale native image storage after mode transitions

Pillow (pip)

### Summary Pillow multi-frame image loaders can retain native `ImagingCore` storage allocated for one frame while changing the Python-side image `mode` and decoder tiles for a later frame. If frame 0 allocates storage for a narrow mode such as `L`, and a later frame of the same dimensions switches to a wider mode such as `RGB` or `CMYK`, Pillow may…

First seen: 22 Oct 2026
Last update: 22 Oct 2026, 16:00 UTC
Fixed in: Pillow 13.0.0
Identifiers: CVE-2026-96639
CVSS: 9.8
Source: GitHub advisory
On the menu as: PyPI packages
Python

Check this repository for exposure to one security incident from pwned.coffee. Report first, change nothing until I say so.

## Pillow multi-frame loaders can reuse stale native image storage after mode transitions
Severity: critical. Patch status: patched.
Affected: Pillow (pip)
Fixed in: Pillow 13.0.0
Ids: CVE-2026-96639

### Summary Pillow multi-frame image loaders can retain native `ImagingCore` storage allocated for one frame while changing the Python-side image `mode` and decoder tiles for a later frame. If frame 0 allocates storage for a narrow mode such as `L`, and a later frame of the same dimensions switches to a wider mode such as `RGB` or `CMYK`, Pillow may…

## Steps
1. Search every lockfile and manifest (package-lock.json, yarn.lock, pnpm-lock.yaml, requirements*.txt, poetry.lock, uv.lock, composer.lock, go.sum, Cargo.lock, Gemfile.lock) for `Pillow`. For each hit, compare the installed version with the fix on the same major line: Pillow 13.0.0. If it's lower, give the exact upgrade command for the package manager this repo uses.

## Report
A table: file, product or package, version in use, affected yes/no, exact fix. Then anything a human has to check outside the repo.

If you have the pwned.coffee MCP server (https://pwned.coffee/mcp), call lookup_cve("CVE-2026-96639") for the latest, and check_repo with this repo's lockfiles, Dockerfiles and workflows for a full receipt.
Sources: https://github.com/advisories/GHSA-v9pv-5gc8-w2m6 https://github.com/python-pillow/Pillow/commit/78d97d994579aef81aafe123773d525f40f2522a https://github.com/python-pillow/Pillow/pull/10105 https://github.com/python-pillow/Pillow/security/advisories/GHSA-v9pv-5gc8-w2m6 https://nvd.nist.gov/vuln/detail/CVE-2026-96639
https://pwned.coffee/i/pillow-multi-frame-loaders-can-reuse-stale-native-image-cve-2026-96639

Sources

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