---
id: CVE-2026-112399
title: >-
  Pillow: APNG background disposal allocates full canvas before decompression
  bomb check
summary: >-
  Pillow is a Python imaging library. From 8.1.0 until 13.0.0, Pillow can
  allocate an APNG disposal background at the full canvas size before applying
  the decompression-bomb check. A crafted APNG with a small first frame, a very
  large decl…
severity: high
cvss: 8.7
cvssVector: 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N'
cvssSource: cna
cwe:
  - CWE-789
vendor: python-pillow
product: Pillow
affected:
  - 'Pillow >= 8.1.0, < 13.0.0'
published: '2026-10-19'
updated: '2026-10-19'
sourceUpdated: '2026-10-19T21:10:11.266Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-112399'
references:
  - url: >-
      https://github.com/python-pillow/Pillow/security/advisories/GHSA-5xm2-6676-qcp9
    label: >-
      https://github.com/python-pillow/Pillow/security/advisories/GHSA-5xm2-6676-qcp9
  - url: >-
      https://github.com/python-pillow/Pillow/commit/f1acfc54c53502948d0d14121872061df931db48
    label: >-
      https://github.com/python-pillow/Pillow/commit/f1acfc54c53502948d0d14121872061df931db48
  - url: 'https://github.com/python-pillow/Pillow/releases/tag/13.0.0'
    label: 'https://github.com/python-pillow/Pillow/releases/tag/13.0.0'
tags:
  - cve.org
ingestedAt: '2026-10-19T21:43:56.128Z'
---

## Overview

Pillow is a Python imaging library. From 8.1.0 until 13.0.0, Pillow can allocate an APNG disposal background at the full canvas size before applying the decompression-bomb check. A crafted APNG with a small first frame, a very large declared canvas, and background disposal or first-frame OP_PREVIOUS reaches PngImageFile._seek while Image.open() positions frame zero. The full-canvas allocation occurs inside Image.open() without requiring pixel loading or frame iteration. This can exhaust memory and deny service. This issue is fixed in version 13.0.0.

## Affected

- `Pillow >= 8.1.0, < 13.0.0`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.