HIGH8.7

PYSEC-2026-4157

pypdf: Possible long runtimes when generating appearance streams

Quick fix

PYSEC-2026-4157 — pypdf: upgrade to the fixed version with the command below.

pip install --upgrade 'pypdf>=6.19.0'

Details

### Impact

An attacker who uses this vulnerability can craft a PDF which leads to long runtimes. This requires updating form field values with flattening enabled, which triggers appearance stream generation.

### Patches

This has been fixed in [pypdf==6.19.0](https://github.com/py-pdf/pypdf/releases/tag/6.19.0).

### Workarounds

If you cannot upgrade yet, consider applying the changes from PR [#4087](https://github.com/py-pdf/pypdf/pull/4087).

Are you affected?

Enter the version of the package you're using.

Affected packages

PyPI/pypdf

Introduced in: 0Fixed in: 6.19.0

Fixpip install --upgrade 'pypdf>=6.19.0'

References

https://github.com/py-pdf/pypdf/security/advisories/GHSA-php9-fj8v-98fj[WEB]
https://nvd.nist.gov/vuln/detail/CVE-2026-102998[ADVISORY]
https://github.com/py-pdf/pypdf/pull/4087[WEB]
https://github.com/py-pdf/pypdf/commit/959467a9b95be83e2dc5ae873ece5f371263ede7[WEB]
https://github.com/py-pdf/pypdf[PACKAGE]
https://github.com/py-pdf/pypdf/releases/tag/6.19.0[WEB]
https://pypi.org/project/pypdf[PACKAGE]
https://github.com/advisories/GHSA-php9-fj8v-98fj[ADVISORY]