MEDIUM5.3

PYSEC-2026-3021

pypdf has long runtimes for wrong size values in cross-reference and object streams

Quick fix

PYSEC-2026-3021 — pypdf: upgrade to the fixed version with the command below.

pip install --upgrade 'pypdf>=6.10.1'

Details

### Impact

An attacker who uses this vulnerability can craft a PDF which leads to long runtimes. This requires cross-reference streams with wrong large `/Size` values or object streams with wrong large `/N` values.

### Patches

This has been fixed in [pypdf==6.10.1](https://github.com/py-pdf/pypdf/releases/tag/6.10.1).

### Workarounds

If you cannot upgrade yet, consider applying the changes from PR [#3733](https://github.com/py-pdf/pypdf/pull/3733).

Are you affected?

Enter the version of the package you're using.

Affected packages

PyPI/pypdf

Introduced in: 0Fixed in: 6.10.1

Fixpip install --upgrade 'pypdf>=6.10.1'

References

https://github.com/py-pdf/pypdf/security/advisories/GHSA-jj6c-8h6c-hppx[WEB]
https://nvd.nist.gov/vuln/detail/CVE-2026-41168[ADVISORY]
https://github.com/py-pdf/pypdf/pull/3733[WEB]
https://github.com/py-pdf/pypdf/commit/62338e9d36419cf193ccec7331784f45df1d70b3[WEB]
https://github.com/py-pdf/pypdf[PACKAGE]
https://github.com/py-pdf/pypdf/releases/tag/6.10.1[WEB]
https://pypi.org/project/pypdf[PACKAGE]
https://github.com/advisories/GHSA-jj6c-8h6c-hppx[ADVISORY]