CVE-2023-36464: PYSEC-2026-3008 - pypdf and PyPDF2 possible Infinite Loop when a comment isn't followed by a character

CVE-2023-36464 · Severity: low · CVSS 3.1 · Published 2026-07-13

pypdf and PyPDF2 possible Infinite Loop when a comment isn't followed by a character

Technologies: pypdf (PyPI), pypdf2 (PyPI). Vendors: PyPI.

Quick answers

Is CVE-2023-36464 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2023-36464 being exploited in the wild.
How severe is CVE-2023-36464?
Low severity, with a CVSS score of 3.1, published 13 July 2026.
Which products and versions are affected?
pypdf (PyPI) ECOSYSTEM:introduced=3.1.0,fixed=3.9.0; pypdf2 (PyPI) ECOSYSTEM:introduced=2.2.0,fixed=3.9.0, ECOSYSTEM:introduced=2.2.0,last_affected=3.0.1.
Is there a fix for CVE-2023-36464?
Yes. pypdf (PyPI): upgrade to 3.9.0 or later; pypdf2 (PyPI): upgrade to 3.9.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
Am I affected by CVE-2023-36464?
Check whether you run pypdf (PyPI) or pypdf2 (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 3.9.0 or later
    pip install "pypdf>=3.9.0"
  • pypdf2 (PyPI): upgrade to 3.9.0 or later
    pip install "pypdf2>=3.9.0"

Affected products

  • pypdf (PyPI) ECOSYSTEM:introduced=3.1.0,fixed=3.9.0
  • pypdf2 (PyPI) ECOSYSTEM:introduced=2.2.0,fixed=3.9.0, ECOSYSTEM:introduced=2.2.0,last_affected=3.0.1

Identifiers

  • CVE-2023-36464
  • GHSA-4vvm-4w3v-6mr8
  • PYSEC-2026-1835
  • PYSEC-2026-3008

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