CVE-2026-79611
Received
Received - Intake
Xen Hypervisor VMEntry Failure Due to Debug State
Vulnerability report for CVE-2026-79611, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.
Publication date: 2026-10-13
Last updated on: 2026-10-13
Assigner: Xen Project
Description
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.
CVSS Scores
EPSS Scores
| Probability: | |
| Percentile: |
Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| xen | xen | From 4.17.x (inc) to 4.21.x (inc) |
Helpful Resources
Exploitability
CWE
KEV
| CWE ID | Description |
|---|---|
| CWE-UNKNOWN |
