Description (CNA)
A reachable assertion in the illumos bhyve instruction emulator allows a guest to panic the host. When emulating a REP-prefixed MOVS or STOS instruction that accesses guest MMIO, vie_emulate_movs() and vie_emulate_stos() in usr/src/uts/intel/io/vmm/vmm_instruction_emul.c do not clear the VIES_REPEAT status flag on the final iteration. For MMIO regions emulated in the kernel (the local APIC, I/O APIC and HPET), the stale flag causes a VERIFY assertion in vie_advance_pc() to fail, and the host panics. A privileged user within a guest VM can issue a REP MOVS or REP STOS instruction against the local APIC page to cause a denial of service of the host and every other guest running on it. The flaw has existed since 2020 (illumos-gate commit e0c0d44e), and affects any illumos distribution prior to illumos-gate commit 696ecf8d.
Affected (CNA)
| Vendor / product | Versions |
|---|---|
| illumos / illumos-gate | affected e0c0d44e917080841514d0dd031a696c74e8c435 before 696ecf8debceed9dc33937d8c8e111e4aeebfdae |
| OmniOS / OmniOS | affected any before r151054; affected r151058 before r151058w; affected r151056 before r151056aw; affected r151054 before r151054bw |
CWE
CWE-617
References
- https://illumos.topicbox.com/groups/developer/T697a32b688807e56/cve-2026-102916-18491-bhyve-rep-prefix-instr-emulation-fumbles-flags
- https://illumos.org/issues/18491
- https://github.com/illumos/illumos-gate/commit/696ecf8debceed9dc33937d8c8e111e4aeebfdae
ADP enrichment
No English description supplied.
No references supplied.
No English description supplied.