---
id: CVE-2026-112406
title: 'Pillow: Infinite loop in PdfParser.rewrite_pages on page tree Parent cycle'
summary: >-
  Pillow is a Python imaging library. From 5.1.0 until 13.0.0, Pillow can enter
  an infinite loop while rewriting PDF pages. PdfParser.rewrite_pages() follows
  Parent relationships without detecting a cycle in the page tree. An attacker
  can …
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-835
vendor: python-pillow
product: Pillow
affected:
  - 'Pillow >= 5.1.0, < 13.0.0'
published: '2026-10-19'
updated: '2026-10-19'
sourceUpdated: '2026-10-19T21:31:49.946Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-112406'
references:
  - url: >-
      https://github.com/python-pillow/Pillow/security/advisories/GHSA-f2g6-542v-9j58
    label: >-
      https://github.com/python-pillow/Pillow/security/advisories/GHSA-f2g6-542v-9j58
  - url: >-
      https://github.com/python-pillow/Pillow/commit/b3ebf20c694f2f12537a629c30229a1d5a53f777
    label: >-
      https://github.com/python-pillow/Pillow/commit/b3ebf20c694f2f12537a629c30229a1d5a53f777
  - 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: '2026-10-19T21:43:56.114Z'
---

## Overview

Pillow is a Python imaging library. From 5.1.0 until 13.0.0, Pillow can enter an infinite loop while rewriting PDF pages. PdfParser.rewrite_pages() follows Parent relationships without detecting a cycle in the page tree. An attacker can supply a cyclic PDF to an application that appends an image to that PDF. This can hold the worker at full CPU and deny service. This issue is fixed in version 13.0.0.

## Affected

- `Pillow >= 5.1.0, < 13.0.0`

## Remediation

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