CVE-2026-42492 Details
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.
A vulnerability exists in Xen versions 4.21 and later, where unprivileged domains can disrupt Xenstore's operation. This issue arises from a new domain state management feature that inadvertently allows unprivileged domains to trigger an error path, causing a denial-of-service condition that could affect the entire host. In rare cases, this disruption might lead to a hypervisor crash with similar host-wide effects.
Applying the provided patch resolves this vulnerability. Note that this patch is intended for the stable branches of Xen and may not apply cleanly to the most recent release tarball. Users are encouraged to update to the tip of the stable branch before applying the patch.
Metrics
CVSS 4.0 Severity and Vector Strings:
VolerionCVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
Volerion
Assessed Jul 28, 2026CISA-ADP
Assessed Jul 28, 2026References to Advisories, Solutions, and Tools
By selecting these links, you will be leaving this site. These are references gathered from the official CVE record and are not endorsed by Volerion.
| URL | Source(s) | Tag(s) |
|---|---|---|
| http://www.openwall.com/lists/oss-security/2026/07/28/13 | CVE | |
| http://xenbits.xen.org/xsa/advisory-496.html | CVE | |
| https://xenbits.xenproject.org/xsa/advisory-496.html | [email protected] | AdvisoryRemedyVendor |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-459 | Incomplete Cleanup | CISA-ADP |
Affected Products
| Product | Versions |
|---|---|
| Xen | >= 4.21 |
CPE
Remediation
| |
Change History
4 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jul 28, 2026 | CVE Modified | CVE |
| Jul 28, 2026 | CVE Modified | CISA-ADP |
| Jul 28, 2026 | CVE Modified | CVE |
| Jul 28, 2026 | New CVE Received | [email protected] |