# CVE-2026-62426: Xen Project Xen denial of service via unfair sysctl and platform-op locks

Source: https://junglewise.ai/threats/cve-2026-62426-xen-project-xen-denial-of-service-via-unfair-sysctl-and-platform  
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-2026-62426 · Severity: info · CVSS 0 · Published 2026-07-28

A vulnerability in the Xen hypervisor, a tool used to run multiple virtual machines on a single physical server, could allow a less-privileged user to disrupt the entire system. By repeatedly requesting certain system management operations, an attacker can block more important administrative tasks from completing. This can lead to a total system freeze or a significant slowdown, impacting all services running on the affected 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-2026-62426 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-62426 being exploited in the wild.

**How severe is CVE-2026-62426?** Informational severity, with a CVSS score of 0, published 28 July 2026.

**Which products and versions are affected?** Xen Project Xen 4.0 and later.

**Is there a fix for CVE-2026-62426?** 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-2026-62426 attacked?** It is attacked with local access, in an operating system.

**Am I affected by CVE-2026-62426?** 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 Xen hypervisor utilizes system-wide locks for sysctl and platform operations to prevent parallel execution. However, these locks lack fairness in their acquisition mechanism. Furthermore, when XSM/Flask is enabled, the lock is acquired before permission checks are performed. A local attacker in a less-privileged domain (such as a Xenstore domain or a restricted control domain) can exploit this lack of fairness to repeatedly acquire the lock, effectively stalling more privileged entities and causing a Denial of Service (DoS) for the entire host. The issue is addressed in XSA-499 via patches that reorder permission checks and improve locking logic.

## Affected products

- Xen Project Xen 4.0 and later

## Timeline

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

## References

- [https://xenbits.xenproject.org/xsa/advisory-499.html](https://xenbits.xenproject.org/xsa/advisory-499.html)

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