CVE-2026-42492 vIRQ event channel binding may break Xenstore
Unprivileged domains can trigger an error path that tears down an uninitialized bitmap, breaking Xenstore and causing denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-42492?
CVE-2026-42492 is a high-severity vulnerability in Xen, published on 28 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-459
Which versions are affected by CVE-2026-42492?
How do I fix CVE-2026-42492?
Apply the vendor's patch.
Is CVE-2026-42492 being exploited?
There is no known exploitation of CVE-2026-42492 in the wild and no public exploit code.
Sources
Also known as ALPINE-CVE-2026-42492, GHSA-2hv5-3qjg-gjqr, UBUNTU-CVE-2026-42492.