CVE-2026-27026: pypdf possibly has long runtimes for malformed FlateDecode streams
(updated )
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.
References
- github.com/advisories/GHSA-9mvc-8737-8j8h
- github.com/py-pdf/pypdf
- github.com/py-pdf/pypdf/commit/7905842d833f899f1d3228af7e7467ad80277016
- github.com/py-pdf/pypdf/pull/3644
- github.com/py-pdf/pypdf/releases/tag/6.7.1
- github.com/py-pdf/pypdf/security/advisories/GHSA-9mvc-8737-8j8h
- nvd.nist.gov/vuln/detail/CVE-2026-27026
Code Behaviors & Features
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