PYSEC-2026-1830
PyPDF's Manipulated FlateDecode streams can exhaust RAM
Quick fix
PYSEC-2026-1830 — pypdf: upgrade to the fixed version with the command below.
pip install --upgrade 'pypdf>=6.0.0'Details
### Impact An attacker who uses this vulnerability can craft a PDF which leads to the RAM being exhausted. This requires just reading the file if a series of FlateDecode filters is used on a malicious cross-reference stream. Other content streams are affected on explicit access.
### Patches This has been fixed in [pypdf==6.0.0](https://github.com/py-pdf/pypdf/releases/tag/6.0.0).
### Workarounds If you cannot upgrade yet, you might want to implement the workaround for `pypdf.filters.decompress` yourself: https://github.com/py-pdf/pypdf/blob/0dd57738bbdcdb63f0fb43d8a6b3d222b6946595/pypdf/filters.py#L72-L143
### References This issue has been reported in #3429 and fixed in #3430.
Are you affected?
Enter the version of the package you're using.
Affected packages
References
- https://github.com/py-pdf/pypdf/security/advisories/GHSA-7hfw-26vp-jp8m[WEB]
- https://nvd.nist.gov/vuln/detail/CVE-2025-55197[ADVISORY]
- https://github.com/py-pdf/pypdf/issues/3429[WEB]
- https://github.com/py-pdf/pypdf/pull/3430[WEB]
- https://github.com/py-pdf/pypdf[PACKAGE]
- https://github.com/py-pdf/pypdf/blob/0dd57738bbdcdb63f0fb43d8a6b3d222b6946595/pypdf/filters.py#L72-L143[WEB]
- https://github.com/py-pdf/pypdf/releases/tag/6.0.0[WEB]
- https://pypi.org/project/pypdf[PACKAGE]
- https://github.com/advisories/GHSA-7hfw-26vp-jp8m[ADVISORY]