https://seclists.org/oss-sec/2026/q4/148: Xen Security Advisory 520 v2 (CVE-2026-102700) - gnttab: cache-flush handling may cause page fence leak
Published Oct 13, 2026
·Updated
Affected Software
1 affected component
Xen Project Xen>=4.5<=4.20
Frequently Asked Questions
1
What conditions are needed to trigger the reference leak?
The affected cache-flush error path must be reached with a specified page owned by a special system domain. The advisory identifies DOM_IO and DOM_COW as system domains that can have memory pages assigned to them.
2
Which deployments should be treated as affected?
Affected deployments are x86 systems running Xen versions 4.5 through 4.20. Arm systems, Xen 4.4 and older, and Xen 4.21 and newer are not affected.
3
What can be done if an update cannot be deployed immediately?
The advisory states that there is no known mitigation. Organizations should prioritize updating affected x86 Xen installations when a fixed version is available.
4
What operational impact should responders expect?
The most likely impact is denial of service against Domain 0, which is likely to affect the entire host, or against another domain.