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PYSEC-2026-4155
pypdf: Possible large memory usage when parsing font data
Quick fix
PYSEC-2026-4155 — pypdf: upgrade to the fixed version with the command below.
pip install --upgrade 'pypdf>=6.18.1'Details
### Impact
An attacker who uses this vulnerability can craft a PDF which leads to large memory consumption. This requires parsing the `/Widths` entry of a TrueType or Type1 fonts with unusually large values, for example during text extraction.
### Patches
This has been fixed in [pypdf==6.18.1](https://github.com/py-pdf/pypdf/releases/tag/6.18.1).
### Workarounds
If you cannot upgrade yet, consider applying the changes from PR [#4072](https://github.com/py-pdf/pypdf/pull/4072).
Are you affected?
Enter the version of the package you're using.
Affected packages
References
- https://github.com/py-pdf/pypdf/security/advisories/GHSA-g9cg-prrw-2r8q[WEB]
- https://nvd.nist.gov/vuln/detail/CVE-2026-102996[ADVISORY]
- https://github.com/py-pdf/pypdf/pull/4072[WEB]
- https://github.com/py-pdf/pypdf/commit/0fb26eb8cdd01c44b3b2c9fe8329751be2f7cfd5[WEB]
- https://github.com/py-pdf/pypdf[PACKAGE]
- https://github.com/py-pdf/pypdf/releases/tag/6.18.1[WEB]
- https://pypi.org/project/pypdf[PACKAGE]
- https://github.com/advisories/GHSA-g9cg-prrw-2r8q[ADVISORY]