Vulnerability · Published Jul 28, 2026 · Assigned by XEN
CVE-2026-42492vIRQ event channel binding may break Xenstore
High 7.5
In plain English
A high-severity security flaw in Xen from Xen. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 49% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine:v3.24 | xen | 4.21.2-r0 | ALPINE-CVE-2026-42492 |
| Debian:12 | xen | no fix listed | DEBIAN-CVE-2026-42492 |
| Debian:13 | xen | no fix listed | DEBIAN-CVE-2026-42492 |
| Debian:14 | xen | no fix listed | DEBIAN-CVE-2026-42492 |
| Ubuntu:22.04:LTS | xen | no fix listed | UBUNTU-CVE-2026-42492 |
| Ubuntu:24.04:LTS | xen | no fix listed | UBUNTU-CVE-2026-42492 |
| Ubuntu:26.04:LTS | xen | no fix listed | UBUNTU-CVE-2026-42492 |
| Ubuntu:26.10 | xen | no fix listed | UBUNTU-CVE-2026-42492 |
Affected products (as reported)
Weakness: CWE-459 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H