CVE-2026-42493

Name	CVE-2026-42493
Description	Addressing certain issues, in particular related to operations which may take excessively long and therefore would need preemption, has turned out overly costly. Since alternatives (HVM/PVH: HAP, PV: shim) are commonly available, the decision was to deprecate the functionality, while still retaining it for people to use at their own (security) risk. Memory-wise small enough guests may still be okay to run.
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)
References	DSA-6424-1

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
xen (PTS)	bullseye	4.14.6-1	vulnerable
	bullseye (security)	4.14.5+94-ge49571868d-1	vulnerable
	bookworm, bookworm (security)	4.17.5+72-g01140da4e8-1	vulnerable
	trixie	4.20.2+37-g61ff35323e-0+deb13u1	vulnerable
	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
xen	source	bullseye	(unfixed)	end-of-life
xen	source	trixie	4.20.3+127-gc42374a105-0+deb13u1		DSA-6424-1
xen	source	(unstable)	4.20.3+127-gc42374a105-1

[bullseye] - xen <end-of-life> (out of LTS support)
https://xenbits.xen.org/xsa/advisory-495.html