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CVE PROGRAM SOURCE RECORD5.5 Medium

CVE-2026-79611

VMX: VMentry failure with branch tracing and blocked states

Description

For XSA-308 logic was introduced, as VMX VMEntry checks do not like the exact combination of state which occurs when #DB in intercepted, Single Stepping is active, and blocked by STI/MovSS is active, despite this being a legitimate state to be in. The resulting VMEntry failure is fatal to the guest. Sadly there is another special sub-case of the above, with branch tracing enabled. In that case the prior adjustment would still cause a VMentry failure, as before fatal to the guest.

Affected products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

Xen Xen

Default version status: unknown

  • consult Xen advisory XSA-518unknown

References