CVE-2026-27026

pypdf is a free and open-source pure-python PDF library. Prior to 6.7.1, an attacker who uses this vulnerability can craft a PDF which leads to long runtimes. This requires a malformed /FlateDecode stream, where the byte-by-byte decompression is used. This vulnerability is fixed in 6.7.1.
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
NISTPrimary
UNKNOWN
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Awaiting analysis
This vulnerability is currently awaiting analysis.
Base Score
CVSS 3.x
EPSS Score
Percentile: Unknown
Common Weakness Enumeration
References
https://github.com/py-pdf/pypdf/commit/7905842d833f899f1d3228af7e7467ad80277016
https://github.com/py-pdf/pypdf/pull/3644
https://github.com/py-pdf/pypdf/releases/tag/6.7.1
https://github.com/py-pdf/pypdf/security/advisories/GHSA-9mvc-8737-8j8h