CVE-2026-27026

Name	CVE-2026-27026
Description	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.
Source	CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
pypdf (PTS)	bookworm	3.4.1-1+deb12u1	vulnerable
	forky, sid, trixie	5.4.0-1	vulnerable
pypdf2 (PTS)	bullseye	1.26.0-4+deb11u1	vulnerable
	bookworm	2.12.1-3+deb12u1	vulnerable

The information below is based on the following data on fixed versions.

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
pypdf	source	(unstable)	(unfixed)
pypdf2	source	(unstable)	(unfixed)

Notes

https://github.com/py-pdf/pypdf/security/advisories/GHSA-9mvc-8737-8j8h
https://github.com/py-pdf/pypdf/pull/3644
Fixed by: https://github.com/py-pdf/pypdf/commit/7905842d833f899f1d3228af7e7467ad80277016 (6.7.1)