CVE-2026-23558 grant table v2 race in status page mapping

High 7.8 Published 19 May 2026 Updated 20 May 2026

A race condition in Xen hypervisor allows guest VMs to trigger use-after-free, potentially leading to privilege escalation or code execution.

Exploited in the wild: Not known
Login needed: Any signed-in user
Attackable: Local or same network only
Victim action needed: Not needed
Fix: Available

What is CVE-2026-23558?

CVE-2026-23558 is a high-severity vulnerability in Xen Xen, published on 19 May 2026. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

The adjustments made for XSA-379 as well as those subsequently becoming XSA-387 still left a race window, when a HVM or PVH guest does a grant table version change from v2 to v1 in parallel with mapping the status page(s) via XENMEM_add_to_physmap. Some of the status pages may then be freed while mappings of them would still be inserted into the guest's secondary (P2M) page tables.

Weakness: CWE-362

Which versions are affected by CVE-2026-23558?

It affects 1 product.

Products include Xen Xen.

How do I fix CVE-2026-23558?

Apply the vendor's patch.

Is CVE-2026-23558 being exploited?

There is no known exploitation of CVE-2026-23558 in the wild and no public exploit code.

All Xen Xen vulnerabilities

Sources

Also known as ALPINE-CVE-2026-23558, DEBIAN-CVE-2026-23558, GHSA-4qf9-g5cf-cx9j, UBUNTU-CVE-2026-23558.