CVE-2026-109399

Name	CVE-2026-109399
Description	SWUpdate through 2026.05.1 contains an improper certificate validation vulnerability in crypto/swupdate_cms_verify_openssl.c that trusts untrusted X.509 certificates embedded in CMS SignedData for chain building. Attackers holding a signing key from a sibling intermediate under the same root can embed that intermediate in the signature to install malicious updates.
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
swupdate (PTS)	bookworm	2022.12+dfsg-4+deb12u2	vulnerable
	trixie	2024.12.1+dfsg-3+deb13u2	vulnerable
	forky	2026.05.1+git20261001+dfsg-1	vulnerable
	sid	2026.05.1+git20261001+dfsg-2	vulnerable

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

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

https://groups.google.com/g/swupdate/c/dsoMcGFnEns