{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-79611","assignerOrgId":"23aa2041-22e1-471f-9209-9b7396fa234f","state":"PUBLISHED","assignerShortName":"XEN","dateReserved":"2026-08-25T07:35:05.290Z","datePublished":"2026-10-13T15:44:56.361Z","dateUpdated":"2026-10-20T17:31:41.971Z"},"containers":{"cna":{"title":"VMX: VMentry failure with branch tracing and blocked states","datePublic":"2026-10-13T12:00:00.000Z","descriptions":[{"lang":"en","value":"For XSA-308 logic was introduced, as VMX VMEntry checks do not like the\nexact combination of state which occurs when #DB in intercepted, Single\nStepping is active, and blocked by STI/MovSS is active, despite this being\na legitimate state to be in.  The resulting VMEntry failure is fatal to\nthe guest.\n\nSadly there is another special sub-case of the above, with branch tracing\nenabled.  In that case the prior adjustment would still cause a VMentry\nfailure, as before fatal to the guest."}],"impacts":[{"descriptions":[{"lang":"en","value":"HVM/PVH guest userspace code may be able to crash the guest, resulting\nin a guest Denial of Service."}]}],"affected":[{"defaultStatus":"unknown","product":"Xen","vendor":"Xen","versions":[{"status":"unknown","version":"consult Xen advisory XSA-518"}]}],"configurations":[{"lang":"en","value":"All versions of Xen are affected.\n\nOnly systems supporting VMX hardware virtual extensions (Intel, VIA or\nZhaoxin CPUs) are affected.  Arm as well as AMD and Hygon systems are\nunaffected.\n\nOnly HVM/PVH guests are affected.  PV guests cannot leverage the\nvulnerability."}],"workarounds":[{"lang":"en","value":"Running only PV guests will avoid this vulnerability.\n\nRunning HVM guests on only AMD or Hygon hardware will also avoid this\nvulnerability."}],"credits":[{"lang":"en","type":"finder","value":"This issue was discovered by Claude Opus and diagnosed as a security issue\nby Teddy Astie of Vates."}],"references":[{"url":"https://xenbits.xenproject.org/xsa/advisory-518.html"}],"providerMetadata":{"orgId":"23aa2041-22e1-471f-9209-9b7396fa234f","shortName":"XEN","dateUpdated":"2026-10-13T15:44:56.361Z"}},"adp":[{"title":"CVE Program Container","references":[{"url":"http://xenbits.xen.org/xsa/advisory-518.html"},{"url":"http://www.openwall.com/lists/oss-security/2026/10/13/7"}],"providerMetadata":{"orgId":"af854a3a-2127-422b-91ae-364da2661108","shortName":"CVE","dateUpdated":"2026-10-13T16:13:51.786Z"}},{"problemTypes":[{"descriptions":[{"type":"CWE","cweId":"CWE-843","lang":"en","description":"CWE-843 Access of Resource Using Incompatible Type ('Type Confusion')"}]}],"metrics":[{"cvssV3_1":{"scope":"UNCHANGED","version":"3.1","baseScore":5.5,"attackVector":"LOCAL","baseSeverity":"MEDIUM","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","integrityImpact":"NONE","userInteraction":"NONE","attackComplexity":"LOW","availabilityImpact":"HIGH","privilegesRequired":"LOW","confidentialityImpact":"NONE"}},{"other":{"type":"ssvc","content":{"timestamp":"2026-10-20T17:31:36.841344Z","id":"CVE-2026-79611","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"title":"CISA ADP Vulnrichment","providerMetadata":{"orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP","dateUpdated":"2026-10-20T17:31:41.971Z"}}]}}