---
id: CVE-2026-96636
title: >-
  Pillow: Decompression-bomb protection bypass via multi-frame seek() in MPO and
  DCX (MpoImageFile.seek / DcxImageFile.seek)
summary: >-
  Pillow is a Python imaging library. Prior to 13.0.0, MpoImageFile.seek() and
  DcxImageFile.seek() reparse later MPO or DCX frames and replace self._size
  without rerunning Image._decompression_bomb_check(). A crafted multi-frame
  image can …
severity: medium
cvss: 6.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H'
cvssSource: cna
cwe:
  - CWE-400
  - CWE-409
vendor: python-pillow
product: Pillow
affected:
  - Pillow < 13.0.0
published: '2026-10-21'
updated: '2026-10-21'
sourceUpdated: '2026-10-21T21:05:20.850Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-96636'
references:
  - url: >-
      https://github.com/python-pillow/Pillow/security/advisories/GHSA-p8hx-v2p6-rp84
    label: >-
      https://github.com/python-pillow/Pillow/security/advisories/GHSA-p8hx-v2p6-rp84
  - url: 'https://github.com/python-pillow/Pillow/pull/10011'
    label: 'https://github.com/python-pillow/Pillow/pull/10011'
  - 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: '2026-10-21T22:18:33.757Z'
---

## Overview

Pillow is a Python imaging library. Prior to 13.0.0, MpoImageFile.seek() and DcxImageFile.seek() reparse later MPO or DCX frames and replace self._size without rerunning Image._decompression_bomb_check(). A crafted multi-frame image can use a tiny first frame to pass Image.open() and then declare an over-limit later frame. Normal frame iteration through seek(), load(), or ImageSequence.Iterator can decode that frame and commit hundreds of megabytes or more, causing memory-exhaustion denial of service. This issue is fixed in version 13.0.0.

## Affected

- `Pillow < 13.0.0`

## Remediation

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