HIGH8.7

PYSEC-2026-4154

pypdf: Possible large memory usage for large /ToUnicode streams (Follow-up 2)

Quick fix

PYSEC-2026-4154 — 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 `/ToUnicode` entry of a font 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 [#4071](https://github.com/py-pdf/pypdf/pull/4071).

Are you affected?

Enter the version of the package you're using.

Affected packages

PyPI/pypdf

Introduced in: 0Fixed in: 6.18.1

Fixpip install --upgrade 'pypdf>=6.18.1'

References

https://github.com/py-pdf/pypdf/security/advisories/GHSA-fp3h-c4fm-7vvf[WEB]
https://nvd.nist.gov/vuln/detail/CVE-2026-102995[ADVISORY]
https://github.com/py-pdf/pypdf/pull/4071[WEB]
https://github.com/py-pdf/pypdf/commit/319d0b823ce2c311a2435e9fd93c13994d32bb51[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-fp3h-c4fm-7vvf[ADVISORY]