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PYSEC-2026-3023

pypdf has inefficient decoding of array-based streams

Quick fix

PYSEC-2026-3023 — pypdf: upgrade to the fixed version with the command below.

pip install --upgrade 'pypdf>=6.9.1'

Details

### Impact An attacker who uses this vulnerability can craft a PDF which leads to long runtimes and/or large memory usage. This requires accessing an array-based stream with lots of entries.

### Patches This has been fixed in [pypdf==6.9.1](https://github.com/py-pdf/pypdf/releases/tag/6.9.1).

### Workarounds If you cannot upgrade yet, consider applying the changes from PR [#3686](https://github.com/py-pdf/pypdf/pull/3686).

Are you affected?

Enter the version of the package you're using.

Affected packages

PyPI/pypdf

Introduced in: 0Fixed in: 6.9.1

Fixpip install --upgrade 'pypdf>=6.9.1'

References

https://github.com/py-pdf/pypdf/security/advisories/GHSA-qpxp-75px-xjcp[WEB]
https://nvd.nist.gov/vuln/detail/CVE-2026-33123[ADVISORY]
https://github.com/py-pdf/pypdf/pull/3686[WEB]
https://github.com/py-pdf/pypdf[PACKAGE]
https://github.com/py-pdf/pypdf/releases/tag/6.9.1[WEB]
https://pypi.org/project/pypdf[PACKAGE]
https://github.com/advisories/GHSA-qpxp-75px-xjcp[ADVISORY]