CVE-2026-55206

Name	CVE-2026-55206
Description	py7zr is a Python-based library and utility to support 7zip archive compression, decompression, encryption and decryption. Prior to 1.1.3, PackInfo._read() in archiveinfo.py used an O(n^2) cumulative sum pattern for attacker-controlled numstreams values parsed from archive headers, allowing a crafted .7z archive to cause excessive CPU consumption during SevenZipFile.init() before extraction. This issue is fixed in version 1.1.3.
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
py7zr (PTS)	bullseye (security), bullseye	0.11.3+dfsg-1+deb11u1	vulnerable
	bookworm	0.11.3+dfsg-5	vulnerable
	trixie	0.22.0+dfsg-1	vulnerable
	forky, sid	1.1.3+dfsg-1	fixed

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

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
py7zr	source	(unstable)	1.1.3+dfsg-1

Notes

https://github.com/miurahr/py7zr/security/advisories/GHSA-h4gh-22qq-72r7
Fixed by: https://github.com/miurahr/py7zr/commit/d7aa3a197d15c75a65b24f796d3a69f83806d3f8 (v1.1.3)