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PYSEC-2026-3024

pypdf has possible long runtimes/large memory usage for large /ToUnicode streams

Quick fix

PYSEC-2026-3024 — pypdf: upgrade to the fixed version with the command below.

pip install --upgrade 'pypdf>=6.7.1'

Details

### Impact

An attacker who uses this vulnerability can craft a PDF which leads to long runtimes and 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==6.7.1](https://github.com/py-pdf/pypdf/releases/tag/6.7.1).

### Workarounds

If you cannot upgrade yet, consider applying the changes from PR [#3646](https://github.com/py-pdf/pypdf/pull/3646).

Are you affected?

Enter the version of the package you're using.

Affected packages

PyPI/pypdf
Introduced in: 0Fixed in: 6.7.1
Fixpip install --upgrade 'pypdf>=6.7.1'

References