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

Source: https://junglewise.ai/threats/cve-2023-36464-pypdf-and-pypdf2-possible-infinite-loop-when-a-comment-isn-t  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-13  
License: CC BY 4.0 with a link back

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)](https://junglewise.ai/threats/technologies/pypdf), [pypdf2 (PyPI)](https://junglewise.ai/threats/technologies/pypdf2). Vendors: [PyPI](https://junglewise.ai/threats/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

  ```sh
  pip install "pypdf>=3.9.0"
  ```

- pypdf2 (PyPI): upgrade to 3.9.0 or later

  ```sh
  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

## Related threats

- [pypdf memory exhaustion in cross-reference stream parsing](https://junglewise.ai/threats/cve-2026-119209-pypdf-is-a-free-and-open-source-pure-python-pdf-library-prior-to)
- [pypdf denial of service via forged encrypted PDF page count](https://junglewise.ai/threats/cve-2026-119208-pypdf-is-a-free-and-open-source-pure-python-pdf-library-prior-to)
- [pypdf excessive memory consumption in strict mode PDF parsing](https://junglewise.ai/threats/cve-2026-119207-pypdf-is-a-free-and-open-source-pure-python-pdf-library-prior-to)
- [pypdf denial of service via crafted page labels](https://junglewise.ai/threats/cve-2026-119206-pypdf-is-a-free-and-open-source-pure-python-pdf-library-prior-to)
- [pypdf infinite loop in DictionaryObject cloning](https://junglewise.ai/threats/cve-2026-119205-pypdf-is-a-free-and-open-source-pure-python-pdf-library-prior-to)