CVE-2026-71870: pypdf is a free and open-source pure-python PDF library. Prior to 6.15.0, a crafted PDF can cause large memory consumption when pypdf/_cmap.

CVE-2026-71870 · Severity: medium · CVSS 4 · Published 2026-08-07

A vulnerability in the pypdf library, a tool used by developers to process and extract text from PDF files, could allow a specially crafted document to crash applications by consuming excessive memory. This could lead to service interruptions or system instability when the software attempts to process a malicious file. Organizations using this library for automated document processing should update to the latest version to prevent potential denial-of-service attacks.

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

Quick answers

Is CVE-2026-71870 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-71870 being exploited in the wild.
How severe is CVE-2026-71870?
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-2026-71870?
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-2026-71870 attacked?
It is attacked with local access, in a software library.
Am I affected by CVE-2026-71870?
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

A vulnerability classified as Uncontrolled Resource Consumption (CWE-400) exists in pypdf versions prior to 6.15.0. The issue occurs when the library parses the /ToUnicode entry of a font containing unusually large values, typically during text extraction processes. An attacker can exploit this by providing a maliciously crafted PDF file that, when processed, causes the application to consume excessive amounts of memory. This is a local attack requiring passive user interaction (opening or processing the file). The vulnerability has been patched in version 6.15.0.

Affected products

  • py-pdf pypdf < 6.15.0

Identifiers

  • CVE-2026-71870
  • GHSA-fp3f-mc75-235c
  • PYSEC-2026-3655

Timeline

  • 2026-08-06: disclosed
  • 2026-08-07: advisory
  • 2026-08-07: patched: Fixed in version 6.15.0

References

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