Pillow: Heap buffer overflow in ImagingJpegDecode

Pillow (pip)

## Summary `JpegImageFile.draft()` — which `Image.thumbnail()` calls automatically — requests 1/2, 1/4 or 1/8 scaled JPEG output and shrinks `self._size` and the tile extents to match, so `_setimage()` allocates a single-row decode buffer of `ceil(W/s)` samples. `ImagingJpegDecode()` sets `cinfo.scale_num`/`scale_denom`, calls `jpeg_start_decompress()`,…

First seen: 20 Oct 2026
Last update: 20 Oct 2026, 20:40 UTC
Fixed in: Pillow 13.0.0
Identifiers: CVE-2026-112403
CVSS: 9.2
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: Heap buffer overflow in ImagingJpegDecode
Severity: critical. Patch status: patched.
Affected: Pillow (pip)
Fixed in: Pillow 13.0.0
Ids: CVE-2026-112403

## Summary `JpegImageFile.draft()` — which `Image.thumbnail()` calls automatically — requests 1/2, 1/4 or 1/8 scaled JPEG output and shrinks `self._size` and the tile extents to match, so `_setimage()` allocates a single-row decode buffer of `ceil(W/s)` samples. `ImagingJpegDecode()` sets `cinfo.scale_num`/`scale_denom`, calls `jpeg_start_decompress()`,…

## 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-2026-112403") for the latest, and check_repo with this repo's lockfiles, Dockerfiles and workflows for a full receipt.
Sources: https://github.com/advisories/GHSA-8g5g-8vmr-9782 https://github.com/python-pillow/Pillow/commit/242a059aedc1935097d9aa1dc3f099750467ba75 https://github.com/python-pillow/Pillow/releases/tag/13.0.0 https://github.com/python-pillow/Pillow/security/advisories/GHSA-8g5g-8vmr-9782 https://nvd.nist.gov/vuln/detail/CVE-2026-112403
https://pwned.coffee/i/pillow-heap-buffer-overflow-in-imagingjpegdecode-cve-2026-112403

Sources

Totalone very hot coffee