CVE-2026-117556

Name	CVE-2026-117556
Description	zchunk before 1.5.5 contains a heap out-of-bounds read vulnerability in read_preface() in src/lib/header.c that passes the total header length instead of remaining bytes to compint parsing functions. Attackers can supply a crafted .zck file whose header ends inside a compressed integer, causing reads past the heap header buffer and crashing the application.
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
zchunk (PTS)	bookworm	1.2.3+ds1-2	vulnerable
	trixie	1.5.1+ds1-1	vulnerable
	forky, sid	1.5.3+ds1-2	vulnerable

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

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
zchunk	source	(unstable)	(unfixed)	unimportant

Notes

https://github.com/zchunk/zchunk/issues/119
https://github.com/zchunk/zchunk/commit/02b371a64bf98245df97315d07c684a0ca5ea1df (1.5.5)
Crash in CLI tool, no security impact