CVE-2026-102997: pypdf: Possible long runtimes for partially malformed FlateDecode streams (Follow-up)

October 1, 2026

An attacker who uses this vulnerability can craft a PDF which leads to long runtimes. This requires a partially malformed /FlateDecode stream, where the byte-by-byte decompression is used.

References

github.com/advisories/GHSA-jw7q-gvrg-4vj3
github.com/py-pdf/pypdf/commit/d9d38cf99b115deb562d3b68f36c33027bc04f79
github.com/py-pdf/pypdf/pull/4073
github.com/py-pdf/pypdf/releases/tag/6.18.1
github.com/py-pdf/pypdf/security/advisories/GHSA-jw7q-gvrg-4vj3
nvd.nist.gov/vuln/detail/CVE-2026-102997

Code Behaviors & Features

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