VM Entry Failure in Xen Hypervisor Under Specific Conditions
CVE-2026-79611
5.5MEDIUM
What is CVE-2026-79611?
A vulnerability in the Xen Hypervisor can cause VM entry failures under specific conditions, including when the #DB (debug exception) is intercepted, single stepping is active, and certain blocking mechanisms (STI/MovSS) are engaged. This situation results in a fatal state for the guest virtual machine, compromising its operational integrity. Moreover, an additional hazard presents itself when branch tracing is enabled, exacerbating the VM entry failure and leading to further complications for guest VMs. As a result, administrators must be vigilant and ensure appropriate mitigations are in place.
Affected Version(s)
Xen consult Xen advisory XSA-518
References
CVSS V3.1
Score:
5.5
Severity:
MEDIUM
Confidentiality:
None
Integrity:
None
Availability:
None
Attack Vector:
Local
Attack Complexity:
Low
Privileges Required:
Low
User Interaction:
None
Scope:
Unchanged
Timeline
Vulnerability published
Vulnerability Reserved
Credit
This issue was discovered by Claude Opus and diagnosed as a security issue
by Teddy Astie of Vates.