CVE-2026-79611

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 3.1

5.5CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

EPSS

0.2% chance of exploitation in the next 30 days; higher than 5% of CVEs (scores of 2026-10-25)

CWE

CWE-843

Published

2026-10-13

Modified

2026-10-20

Record from

the NVD, synced 2026-10-21

References

• https://xenbits.xenproject.org/xsa/advisory-518.html
• http://www.openwall.com/lists/oss-security/2026/10/13/7
• http://xenbits.xen.org/xsa/advisory-518.html

Check your stackJSON