{"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": "2026-10-13T16:13:51.786Z"}, "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"}}]}}

{}

{"affected": [{"affectedData": [{"defaultStatus": "unknown", "product": "Xen", "vendor": "Xen", "versions": [{"status": "unknown", "version": "consult Xen advisory XSA-518"}]}], "source": "security@xen.org"}], "cveTags": [], "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."}], "id": "CVE-2026-79611", "lastModified": "2026-10-13T16:17:23.347", "metrics": {}, "published": "2026-10-13T16:17:23.347", "references": [{"source": "security@xen.org", "url": "https://xenbits.xenproject.org/xsa/advisory-518.html"}], "sourceIdentifier": "security@xen.org", "vulnStatus": "Received"}

{}

{}