Is CVE-2026-42487 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-42487 being exploited in the wild.

How severe is CVE-2026-42487?

High severity, with a CVSS score of 7.9, published 18 June 2026.

Which products and versions are affected?

Xen Project Xen 3.2 and later (x86 only).

Is there a fix for CVE-2026-42487?

No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

How is CVE-2026-42487 attacked?

It is attacked with local access, in an operating system.

Am I affected by CVE-2026-42487?

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.

CVE-2026-42487: Xen x86 HVM race condition in I/O port list traversal

CVE-2026-42487 · Severity: high · CVSS 7.9 · Published 2026-06-18

A vulnerability exists in the Xen hypervisor, which is software used to run multiple virtual machines on a single physical server. A malicious or compromised virtual machine could trigger a crash of the entire physical host, leading to a total service outage for all other virtual machines on that server. In some cases, this could also lead to unauthorized access to data or increased privileges on the system.

Technologies: Xen Project Xen. Vendors: Xen Project.

Quick answers

Is CVE-2026-42487 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-42487 being exploited in the wild.
How severe is CVE-2026-42487?: High severity, with a CVSS score of 7.9, published 18 June 2026.
Which products and versions are affected?: Xen Project Xen 3.2 and later (x86 only).
Is there a fix for CVE-2026-42487?: No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2026-42487 attacked?: It is attacked with local access, in an operating system.
Am I affected by CVE-2026-42487?: 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

A race condition (CWE-362) exists in the Xen hypervisor's handling of I/O port accesses for x86 HVM guests. I/O port translations are managed via linked lists that can be modified by the device model using XEN_DOMCTL_ioport_mapping. The hypervisor failed to properly synchronize list traversal with these updates. An attacker controlling a device model (such as one running in a stub domain or a de-privileged Dom0) can exploit this lack of synchronization to cause a hypervisor crash (DoS), or potentially achieve information disclosure or privilege escalation. The vulnerability affects x86 systems only; ARM systems and PV/PVH guests are not impacted. Patches are available for supported Xen versions.

Affected products

Xen Project Xen 3.2 and later (x86 only)

Timeline

2026-06-09: disclosed: Initial public release of XSA-491
2026-06-18: advisory: NVD publication date

References

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