---
id: CVE-2026-22691
title: >-
  pypdf: pypdf: Denial of Service via malformed PDF startxref entries
  (CVE-2026-22691)
summary: >-
  A flaw was found in pypdf. A remote attacker can exploit this vulnerability by
  crafting a malicious PDF file with malformed startxref entries and excessive
  whitespace characters. This can cause excessively long processing times when
  rebuil…
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: vendor
cwe: CWE-1050
vendor: Red Hat
product: Red Hat Ansible Automation Platform 2
affected:
  - openshift_lightspeed
  - ansible_automation_platform 2
  - enterprise_linux_ai_rhel_ai 3
  - openshift_ai_rhoai
patched:
  - pypdf 6.6.0
published: '2026-01-10'
updated: '2026-10-15'
sourceUpdated: '2026-10-15T11:33:26+00:00'
source: CSAF
sourceUrl: 'https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-22691.json'
references:
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-22691.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-22691'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2428427'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-22691'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-22691'
  - url: >-
      https://github.com/py-pdf/pypdf/commit/294165726b646bb7799be1cc787f593f2fdbcf45
  - url: 'https://github.com/py-pdf/pypdf/pull/3594'
  - url: 'https://github.com/py-pdf/pypdf/releases/tag/6.6.0'
  - url: 'https://github.com/py-pdf/pypdf/security/advisories/GHSA-4f6g-68pf-7vhv'
  - url: 'https://github.com/py-pdf/pypdf'
tags:
  - csaf
  - vex
  - red-hat
  - osv
  - pip
epss: 0.00433
epssPercentile: 0.37456
aliases:
  - GHSA-4f6g-68pf-7vhv
  - PYSEC-2026-1828
ecosystem: pip
ingestedAt: '2026-07-08T18:25:45.466Z'
---

## Overview

A flaw was found in pypdf. A remote attacker can exploit this vulnerability by crafting a malicious PDF file with malformed startxref entries and excessive whitespace characters. This can cause excessively long processing times when rebuilding the cross-reference table in non-strict reading mode, leading to a denial of service.

## Vendor advisories

- **Red Hat VEX** · Moderate · affected: OpenShift Lightspeed, Red Hat Ansible Automation Platform 2, Red Hat Enterprise Linux AI (RHEL AI) 3, Red Hat OpenShift AI (RHOAI) · no fix planned: OpenShift Lightspeed, Red Hat Ansible Automation Platform 2, Red Hat Enterprise Linux AI (RHEL AI) 3, Red Hat OpenShift AI (RHOAI) · updated 2026-10-15 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-22691.json)

**pypdf: pypdf: Denial of Service via malformed PDF startxref entries** — rated Moderate by Red Hat. Released 2026-01-10, updated 2026-10-15.

Affected:

- OpenShift Lightspeed
- Red Hat Ansible Automation Platform 2
- Red Hat Enterprise Linux AI (RHEL AI) 3
- Red Hat OpenShift AI (RHOAI)

No fix planned:

- OpenShift Lightspeed
- Red Hat Ansible Automation Platform 2
- Red Hat Enterprise Linux AI (RHEL AI) 3
- Red Hat OpenShift AI (RHOAI)

## Remediation

Fix deferred

## Package advisory (CVE-2026-22691)

Affected packages:

- `pypdf < 6.6.0`

Patched in:

- `pypdf 6.6.0`

Source: https://osv.dev/vulnerability/GHSA-4f6g-68pf-7vhv