{"id":"CVE-2026-81627","state":"PUBLISHED","title":"Qemu-kvm: vapic writable rom alias can escape the option-rom window and expose locked smram","description":"A flaw was found in QEMU. The VAPIC setup hypercall in hw/i386/vapic.c does not validate that the writable RAM alias remains within the option ROM window. A privileged guest user on a Q35/KVM machine can position this alias over locked SMRAM, bypassing chipset D_LCK protection and injecting code into System Management Mode memory.","publishedAt":"2026-09-18T10:54:03.297Z","updatedAt":"2026-10-30T20:05:12.889Z","severity":{"score":8.2,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H","source":"redhat"},"assigner":"redhat","products":["Red Hat Red Hat Enterprise Linux 10","Red Hat Red Hat Enterprise Linux 6","Red Hat Red Hat Enterprise Linux 7","Red Hat Red Hat Enterprise Linux 8","Red Hat Red Hat Enterprise Linux 9","Red Hat Red Hat Enterprise Linux for NVIDIA 26","Red Hat Red Hat OpenShift Container Platform 4","Red Hat Red Hat OpenShift Container Platform 5","Red Hat Red Hat OpenStack Platform 13 (Queens)"],"affected":[{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 10","packageName":"qemu-kvm","defaultStatus":"affected","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","cpes":["cpe:/o:redhat:enterprise_linux:10"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 6","packageName":"qemu-kvm","defaultStatus":"unaffected","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","cpes":["cpe:/o:redhat:enterprise_linux:6"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 7","packageName":"qemu-kvm","defaultStatus":"affected","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","cpes":["cpe:/o:redhat:enterprise_linux:7"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 7","packageName":"qemu-kvm-ma","defaultStatus":"affected","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","cpes":["cpe:/o:redhat:enterprise_linux:7"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 8","packageName":"virt-devel:rhel/qemu-kvm","defaultStatus":"affected","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","cpes":["cpe:/o:redhat:enterprise_linux:8"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 8","packageName":"virt:rhel/qemu-kvm","defaultStatus":"affected","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","cpes":["cpe:/o:redhat:enterprise_linux:8"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 9","packageName":"qemu-kvm","defaultStatus":"affected","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","cpes":["cpe:/o:redhat:enterprise_linux:9"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux for NVIDIA 26","packageName":"qemu-kvm","defaultStatus":"unknown","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","cpes":["cpe:/a:redhat:enterprise_linux_nvidia:"]},{"vendor":"Red Hat","product":"Red Hat OpenShift Container Platform 4","packageName":"openshift/ose-rhel-coreos-8","defaultStatus":"affected","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","cpes":["cpe:/a:redhat:openshift:4"]},{"vendor":"Red Hat","product":"Red Hat OpenShift Container Platform 4","packageName":"openshift/ose-rhel-coreos-9","defaultStatus":"affected","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","cpes":["cpe:/a:redhat:openshift:4"]},{"vendor":"Red Hat","product":"Red Hat OpenShift Container Platform 5","packageName":"openshift/ose-rhel-coreos-9","defaultStatus":"affected","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","cpes":["cpe:/a:redhat:openshift:5"]},{"vendor":"Red Hat","product":"Red Hat OpenStack Platform 13 (Queens)","packageName":"qemu-kvm-rhev","defaultStatus":"affected","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","cpes":["cpe:/a:redhat:openstack:13"]}],"references":["https://access.redhat.com/security/cve/CVE-2026-81627","https://bugzilla.redhat.com/show_bug.cgi?id=2536950","https://gitlab.com/qemu-project/qemu/-/work_items/4206"],"weaknesses":["CWE-787"],"ingestedAt":"2026-10-30T20:14:06.645Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/81xxx/CVE-2026-81627.json","commit":"d7f5c3fe206091a44e450f13bfe51dc81b8a7843","baselineCommit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-81627","state":"PUBLISHED","datePublished":"2026-09-18T10:54:03.297Z","dateUpdated":"2026-10-30T20:05:12.889Z","assignerShortName":"redhat","assignerOrgId":"53f830b8-0a3f-465b-8143-3b8a9948e749","dateReserved":"2026-08-27T09:01:09.972Z"},"containers":{"cna":{"title":"Qemu-kvm: vapic writable rom alias can escape the option-rom window and expose locked smram","descriptions":[{"lang":"en","value":"A flaw was found in QEMU. The VAPIC setup hypercall in hw/i386/vapic.c does not validate that the writable RAM alias remains within the option ROM window. A privileged guest user on a Q35/KVM machine can position this alias over locked SMRAM, bypassing chipset D_LCK protection and injecting code into System Management Mode memory."}],"affected":[{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 10","packageName":"qemu-kvm","defaultStatus":"affected","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","cpes":["cpe:/o:redhat:enterprise_linux:10"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 6","packageName":"qemu-kvm","defaultStatus":"unaffected","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","cpes":["cpe:/o:redhat:enterprise_linux:6"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 7","packageName":"qemu-kvm","defaultStatus":"affected","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","cpes":["cpe:/o:redhat:enterprise_linux:7"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 7","packageName":"qemu-kvm-ma","defaultStatus":"affected","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","cpes":["cpe:/o:redhat:enterprise_linux:7"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 8","packageName":"virt-devel:rhel/qemu-kvm","defaultStatus":"affected","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","cpes":["cpe:/o:redhat:enterprise_linux:8"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 8","packageName":"virt:rhel/qemu-kvm","defaultStatus":"affected","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","cpes":["cpe:/o:redhat:enterprise_linux:8"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 9","packageName":"qemu-kvm","defaultStatus":"affected","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","cpes":["cpe:/o:redhat:enterprise_linux:9"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux for NVIDIA 26","packageName":"qemu-kvm","defaultStatus":"unknown","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","cpes":["cpe:/a:redhat:enterprise_linux_nvidia:"]},{"vendor":"Red Hat","product":"Red Hat OpenShift Container Platform 4","packageName":"openshift/ose-rhel-coreos-8","defaultStatus":"affected","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","cpes":["cpe:/a:redhat:openshift:4"]},{"vendor":"Red Hat","product":"Red Hat OpenShift Container Platform 4","packageName":"openshift/ose-rhel-coreos-9","defaultStatus":"affected","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","cpes":["cpe:/a:redhat:openshift:4"]},{"vendor":"Red Hat","product":"Red Hat OpenShift Container Platform 5","packageName":"openshift/ose-rhel-coreos-9","defaultStatus":"affected","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","cpes":["cpe:/a:redhat:openshift:5"]},{"vendor":"Red Hat","product":"Red Hat OpenStack Platform 13 (Queens)","packageName":"qemu-kvm-rhev","defaultStatus":"affected","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","cpes":["cpe:/a:redhat:openstack:13"]}],"references":[{"url":"https://access.redhat.com/security/cve/CVE-2026-81627","tags":["vdb-entry","x_refsource_REDHAT"]},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2536950","name":"RHBZ#2536950","tags":["issue-tracking","x_refsource_REDHAT"]},{"url":"https://gitlab.com/qemu-project/qemu/-/work_items/4206"}],"metrics":[{"other":{"content":{"value":"Important","namespace":"https://access.redhat.com/security/updates/classification/"},"type":"Red Hat severity rating"}},{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"LOCAL","availabilityImpact":"HIGH","baseScore":8.2,"baseSeverity":"HIGH","confidentialityImpact":"HIGH","integrityImpact":"HIGH","privilegesRequired":"HIGH","scope":"CHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H","version":"3.1"},"format":"CVSS"}],"problemTypes":[{"descriptions":[{"cweId":"CWE-787","description":"Out-of-bounds Write","lang":"en","type":"CWE"}]}],"providerMetadata":{"shortName":"redhat","orgId":"53f830b8-0a3f-465b-8143-3b8a9948e749","dateUpdated":"2026-10-30T20:05:12.889Z"},"datePublic":"2026-08-26T00:00:00.000Z","x_redhatCweChain":"CWE-787: Out-of-bounds Write","workarounds":[{"lang":"en","value":"The VAPIC TPR optimization can be disabled by preventing the kvmvapic option ROM from loading. When using libvirt, set the following in the guest's domain XML:\n```\n<features>\n  <apic/>\n  <hyperv>\n    <vapic state='off'/>\n  </hyperv>\n</features>\n```\nWhen using QEMU directly, pass `-global kvmvapic.rom=off` on the command line.\n\nThis optimization is only used by 32-bit Windows guests for MMIO-based TPR register access. Linux guests, 64-bit Windows guests, and any guest using x2APIC or MSR-based TPR access are unaffected by disabling it."}],"timeline":[{"lang":"en","time":"2026-09-18T00:00:00.000Z","value":"Reported to Red Hat."},{"lang":"en","time":"2026-08-26T00:00:00.000Z","value":"Made public."}],"credits":[{"lang":"en","value":"Red Hat would like to thank Artem Dinaburg (Trail of Bits) for reporting this issue."}],"x_generator":{"engine":"cvelib 1.8.0"}},"adp":[{"title":"CISA ADP Vulnrichment","references":[{"url":"https://gitlab.com/qemu-project/qemu/-/work_items/4206","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-09-18T15:07:17.054544Z","id":"CVE-2026-81627","options":[{"Exploitation":"poc"},{"Automatable":"no"},{"Technical Impact":"total"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-09-18T15:07:23.968Z"}}]}}}