CVE-2026-42492

Name	CVE-2026-42492
Description	Xenstore, to have an up-to-date picture of the entire system, wants to know of domains appearing and disappearing. To make this more robust, a new XEN_DOMCTL_get_domain_state was introduced. The management of the bitmap underlying that operation is tied into the binding of the VIRQ_DOM_EXC virtual IRQ. Unfortunately an error path there would tear down the bitmap even in cases when it wasn't set up. Unprivileged domains can trigger that error path.
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
xen (PTS)	bullseye	4.14.6-1	fixed
	bullseye (security)	4.14.5+94-ge49571868d-1	fixed
	bookworm, bookworm (security)	4.17.5+72-g01140da4e8-1	fixed
	trixie	4.20.2+37-g61ff35323e-0+deb13u1	fixed
	trixie (security)	4.20.3+127-gc42374a105-0+deb13u1	fixed
	forky, sid	4.20.3+127-gc42374a105-1	fixed

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

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
xen	source	(unstable)	(not affected)

- xen <not-affected> (Vulnerable code introduced later)
https://xenbits.xen.org/xsa/advisory-496.html