Guest-to-SMM code injection via unconstrained VAPIC alias
Published Sep 18, 2026 · Updated Sep 18, 2026
Out-of-bounds write in QEMU's VAPIC setup hypercall allows guest OS users with root access to inject code into locked SMRAM. vapic_map_rom_writable aligns a guest-selected address, trusts a guest-controlled length, and creates a priority-1000 writable RAM alias without confining its base and end to the option-ROM window. Exploitation requires a Q35 guest with KVM acceleration and permits privileged guest code to bypass D_LCK protection and execute injected code in System Management Mode.
Summary
What happened
Out-of-bounds write in QEMU's VAPIC setup hypercall allows guest OS users with root access to inject code into locked SMRAM. vapic_map_rom_writable aligns a guest-selected address, trusts a guest-controlled length, and creates a priority-1000 writable RAM alias without confining its base and end to the option-ROM window. Exploitation requires a Q35 guest with KVM acceleration and permits privileged guest code to bypass D_LCK protection and execute injected code in System Management Mode.
The record
- CVE
- CVE-2026-81627
- Published
- Sep 18, 2026
- Updated
- Sep 18, 2026
- Vendor
- Commonhaus Foundation
- Product
- Red Hat Enterprise Linux 10
- Classifications
- CWE-787, T1068
- Attack vector
- local
- Privileges
- admin
Timeline
How it unfolded
- Sep 18, 2026CVE publishedPublication date reported by the CVE source.
- Sep 18, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Affected versions are unavailable in this record. Check the vendor advisory for version and patch details.
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Activity data is delayed. The latest report is Sep 28, 2026.
Public exploit references
- qemu-vapic-smram-reproducerproof of concept · demonstrated
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Reported exploitation
- Demonstrated guest-to-host escape chainexploit chain
Technologies
Your stack
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Your stack
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