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

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 DLCK protection and injecting code...