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PYSEC-2026-3027

pypdf: Manipulated FlateDecode XFA streams can exhaust RAM

Quick fix

PYSEC-2026-3027 — pypdf: upgrade to the fixed version with the command below.

pip install --upgrade 'pypdf>=6.7.3'

Details

### Impact An attacker who uses this vulnerability can craft a PDF which leads to the RAM being exhausted. This requires accessing the `xfa` property of a reader or writer and the corresponding stream being compressed using `/FlateDecode`.

### Patches This has been fixed in [pypdf==6.7.3](https://github.com/py-pdf/pypdf/releases/tag/6.7.3).

### Workarounds If projects cannot upgrade yet, consider applying the changes from PR [#3658](https://github.com/py-pdf/pypdf/pull/3658).

Are you affected?

Enter the version of the package you're using.

Affected packages

PyPI/pypdf

Introduced in: 0Fixed in: 6.7.3

Fixpip install --upgrade 'pypdf>=6.7.3'

References

https://github.com/py-pdf/pypdf/security/advisories/GHSA-x7hp-r3qg-r3cj[WEB]
https://nvd.nist.gov/vuln/detail/CVE-2026-27888[ADVISORY]
https://github.com/py-pdf/pypdf/pull/3658[WEB]
https://github.com/py-pdf/pypdf/commit/7a4c8246ed48d9d328fb596942271da47b6d109c[WEB]
https://github.com/py-pdf/pypdf[PACKAGE]
https://github.com/py-pdf/pypdf/releases/tag/6.7.3[WEB]
https://pypi.org/project/pypdf[PACKAGE]
https://github.com/advisories/GHSA-x7hp-r3qg-r3cj[ADVISORY]