CVE-2026-42487 x86 HVM I/O port list traversal
A race condition in Xen's HVM I/O port list traversal allows guest users to cause denial of service or potentially execute code.
- 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-2026-42487?
CVE-2026-42487 is a high-severity vulnerability in Xen, published on 18 Jun 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
HVM guest I/O port accesses are subject to either emulation or at least translation. Translations are managed by the device model (via XEN_DOMCTL_ioport_mapping), and hence the linked list used may changed at any time. Traversal of those lists (while handling guest I/O port accesses) therefore needs synchronizing with updates, which was missing so far.
Weakness: CWE-362
Which versions are affected by CVE-2026-42487?
How do I fix CVE-2026-42487?
Apply the vendor's patch.
Is CVE-2026-42487 being exploited?
There is no known exploitation of CVE-2026-42487 in the wild and no public exploit code.
Sources
Also known as ALPINE-CVE-2026-42487, DEBIAN-CVE-2026-42487, GHSA-xx8x-hq3h-f37h, UBUNTU-CVE-2026-42487.