CVE-2026-81627 (GCVE-0-2026-81627)

Vulnerability from cvelistv5 – Published: 2026-09-18 10:54 – Updated: 2026-09-21 11:32
VLAI
Title
Qemu-kvm: vapic writable rom alias can escape the option-rom window and expose locked smram
Summary
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.
Severity
8.2 (High)
CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
SSVC
Exploitation: poc Automatable: no Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-09-18 15:07 UTC
CWE
Assigner
redhat CNA under the redhat root
CNA scorecard B 82/100 over 1036 records in the last 180 days details
References
Impacted products
Date Public
2026-08-26 00:00
Credits
Red Hat would like to thank Artem Dinaburg (Trail of Bits) for reporting this issue.
Show details on NVD website
To clipboard 

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              "defaultStatus": "affected",
              "packageName": "openshift/ose-rhel-coreos-8",
              "product": "Red Hat OpenShift Container Platform 4",
              "vendor": "Red Hat"
            },
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              "vendor": "Red Hat"
            },
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              "cpes": [
                "cpe:/a:redhat:openstack:13"
              ],
              "defaultStatus": "affected",
              "packageName": "qemu-kvm-rhev",
              "product": "Red Hat OpenStack Platform 13 (Queens)",
              "vendor": "Red Hat"
            }
          ],
          "credits": [
            {
              "lang": "en",
              "value": "Red Hat would like to thank Artem Dinaburg (Trail of Bits) for reporting this issue."
            }
          ],
          "datePublic": "2026-08-26T00:00:00.000Z",
          "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."
            }
          ],
          "metrics": [
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                  "namespace": "https://access.redhat.com/security/updates/classification/",
                  "value": "Important"
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                "type": "Red Hat severity rating"
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                "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"
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              "descriptions": [
                {
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                  "description": "Out-of-bounds Write",
                  "lang": "en",
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            "dateUpdated": "2026-09-21T11:32:47.295Z",
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              "url": "https://access.redhat.com/security/cve/CVE-2026-81627"
            },
            {
              "name": "RHBZ#2536950",
              "tags": [
                "issue-tracking",
                "x_refsource_REDHAT"
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            },
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              "url": "https://gitlab.com/qemu-project/qemu/-/work_items/4206"
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          ],
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              "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."
            }
          ],
          "title": "Qemu-kvm: vapic writable rom alias can escape the option-rom window and expose locked smram",
          "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\u0027s domain XML:\n```\n\u003cfeatures\u003e\n  \u003capic/\u003e\n  \u003chyperv\u003e\n    \u003cvapic state=\u0027off\u0027/\u003e\n  \u003c/hyperv\u003e\n\u003c/features\u003e\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."
            }
          ],
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            "engine": "cvelib 1.8.0"
          },
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        }
      },
      "cveMetadata": {
        "assignerOrgId": "53f830b8-0a3f-465b-8143-3b8a9948e749",
        "assignerShortName": "redhat",
        "cveId": "CVE-2026-81627",
        "datePublished": "2026-09-18T10:54:03.297Z",
        "dateReserved": "2026-08-27T09:01:09.972Z",
        "dateUpdated": "2026-09-21T11:32:47.295Z",
        "state": "PUBLISHED"
      },
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}



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