CVE-2026-102997

Description

pypdf is a free and open-source pure-python PDF library. Prior to 6.18.1, a crafted PDF containing a partially malformed /FlateDecode stream with padded data can force pypdf/filters.py to use inefficient byte-by-byte decompression while the earlier recovery counter fails to advance for bytes that successfully decode, causing long runtimes and application unavailability. This is a residual issue after the malformed FlateDecode recovery fix. This issue is fixed in version 6.18.1.

References

• https://github.com/py-pdf/pypdf/commit/d9d38cf99b115deb562d3b68f36c33027bc04f79
• https://github.com/py-pdf/pypdf/pull/4073
• https://github.com/py-pdf/pypdf/releases/tag/6.18.1
• https://github.com/py-pdf/pypdf/security/advisories/GHSA-jw7q-gvrg-4vj3