# CVE-2026-42492: Xen vIRQ event channel binding error in Xenstore

Source: https://junglewise.ai/threats/cve-2026-42492-xen-virq-event-channel-binding-error-in-xenstore  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-28. Updated: 2026-07-28  
License: CC BY 4.0 with a link back

CVE-2026-42492 · Severity: info · CVSS 6.5 · Published 2026-07-28

A vulnerability in the Xen hypervisor's domain management system could allow a standard user or guest virtual machine to disrupt the host's management service (Xenstore). This can lead to a total system-wide denial of service, preventing the host from managing virtual machines or potentially causing the entire physical server to crash. This affects the availability of all services running on the impacted host.

Technologies: [Xen Project Xen](https://junglewise.ai/threats/technologies/xen). Vendors: [Xen Project](https://junglewise.ai/threats/vendors/xen-project).

## Quick answers

**Is CVE-2026-42492 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-42492 being exploited in the wild.

**How severe is CVE-2026-42492?** Informational severity, with a CVSS score of 6.5, published 28 July 2026.

**Which products and versions are affected?** Xen Project Xen 4.21 and onwards.

**Is there a fix for CVE-2026-42492?** A patch was published on 2026-07-28. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-42492 attacked?** It is attacked with local access, in an operating system.

**Am I affected by CVE-2026-42492?** Check whether you run Xen Project Xen at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The vulnerability exists in the handling of the VIRQ_DOM_EXC virtual IRQ binding, which is linked to the XEN_DOMCTL_get_domain_state operation. An error path in the binding logic fails to verify if the underlying bitmap was actually initialized before attempting to tear it down. An unprivileged guest domain can intentionally trigger this error path. Successful exploitation can corrupt the state of Xenstore, leading to a host-wide Denial of Service (DoS) or, in rare cases, a hypervisor crash. The issue was introduced alongside the XEN_DOMCTL_get_domain_state feature in Xen version 4.21.

## Affected products

- Xen Project Xen 4.21 and onwards

## Timeline

- 2026-07-28: disclosed
- 2026-07-28: advisory
- 2026-07-28: patched

## References

- [https://xenbits.xenproject.org/xsa/advisory-496.html](https://xenbits.xenproject.org/xsa/advisory-496.html)

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