---
id: CVE-2026-59937
aliases:
  - GHSA-55h5-xmcq-c37v
  - PYSEC-2026-3610
title: 'pypdf: Possible long runtimes for repeated malformed cross-reference entries '
summary: 'pypdf: Possible long runtimes for repeated malformed cross-reference entries '
severity: medium
vendor: pypdf
product: pypdf
ecosystem: pip
affected:
  - pypdf < 6.14.0
patched:
  - pypdf 6.14.0
published: '2026-07-23'
updated: '2026-09-10'
sourceUpdated: '2026-09-10T03:50:12.272620075Z'
source: OSV
sourceUrl: 'https://osv.dev/vulnerability/GHSA-55h5-xmcq-c37v'
references:
  - url: 'https://github.com/py-pdf/pypdf/security/advisories/GHSA-55h5-xmcq-c37v'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-59937'
  - url: 'https://github.com/py-pdf/pypdf/pull/3887'
  - url: >-
      https://github.com/py-pdf/pypdf/commit/b5fc5aa714f4b696fb9b1deaa35a9e4a4eb50dae
  - url: 'https://github.com/py-pdf/pypdf'
  - url: 'https://github.com/py-pdf/pypdf/releases/tag/6.14.0'
  - url: 'https://github.com/advisories/GHSA-55h5-xmcq-c37v'
tags:
  - osv
  - pip
  - ghsa
epss: 0.0062
epssPercentile: 0.47396
cwe:
  - CWE-400
ingestedAt: '2026-07-23T15:18:37.923Z'
---

## Overview

### Impact

An attacker who uses this vulnerability can craft a PDF which leads to long runtimes. This requires cross-reference streams with repeated malformed cross-reference streams.

### Patches

This has been fixed in [pypdf==6.14.0](https://github.com/py-pdf/pypdf/releases/tag/6.14.0).

### Workarounds

If you cannot upgrade yet, consider applying the changes from PR [#3887](https://github.com/py-pdf/pypdf/pull/3887).

## Affected packages

- `pypdf < 6.14.0`

## Remediation

Upgrade to a patched release:

- `pypdf 6.14.0`