CVE-2026-71852: pypdf excessive iteration in CID font width parsing

CVE-2026-71852 · Severity: medium · CVSS 4 · Published 2026-08-07

A vulnerability in the pypdf library, which is used to process PDF files in Python applications, can allow an attacker to cause significant delays or system crashes. By providing a specially crafted PDF file with unusual font settings, an attacker can force the application to consume excessive memory and processing time. This could lead to a denial-of-service, making the affected application unavailable to users.

Technologies: Pypdf Project Pypdf, pypdf (PyPI). Vendors: Pypdf Project, PyPI.

Quick answers

Is CVE-2026-71852 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-71852 being exploited in the wild.
How severe is CVE-2026-71852?
Medium severity, with a CVSS score of 4, published 7 August 2026.
Which products and versions are affected?
pypdf (PyPI) < 6.15.0, ECOSYSTEM:introduced=0,fixed=6.15.0.
Is there a fix for CVE-2026-71852?
Yes. pypdf (PyPI): upgrade to 6.15.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-71852 attacked?
It is attacked with local access, in a software library.
Am I affected by CVE-2026-71852?
Check whether you run Pypdf Project Pypdf or pypdf (PyPI) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

  • pypdf (PyPI): upgrade to 6.15.0 or later
    pip install "pypdf>=6.15.0"

Technical details

The pypdf library is vulnerable to excessive iteration (CWE-834) when parsing font width entries in CID fonts. An attacker can craft a PDF with unusually large values in these entries, which, when processed during operations like text extraction, leads to long runtimes and high memory usage. The vulnerability is triggered by a lack of sufficient limits on loops during font width parsing. This is a local attack vector requiring the user to process a malicious file (User Interaction: Passive). The issue is fixed in version 6.15.0.

Affected products

  • py-pdf pypdf < 6.15.0

Identifiers

  • CVE-2026-71852
  • GHSA-fwg2-594c-jp42
  • PYSEC-2026-3656

Timeline

  • 2026-08-06: patched: Version 6.15.0 released.
  • 2026-08-07: advisory: GitHub Advisory published.

References

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