{"id":"CVE-2026-102916","title":"A reachable assertion in the illumos bhyve instruction emulator allows a guest to panic the host","summary":"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/i…","severity":"none","cwe":["CWE-617"],"published":"2026-10-09","updated":"2026-10-09","sourceUpdated":"2026-10-09T17:16:43.520","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-102916","references":[{"url":"https://github.com/illumos/illumos-gate/commit/696ecf8debceed9dc33937d8c8e111e4aeebfdae","label":"0ca53633-f0b5-4853-ba72-e0a2e62000d0"},{"url":"https://illumos.org/issues/18491","label":"0ca53633-f0b5-4853-ba72-e0a2e62000d0"},{"url":"https://illumos.topicbox.com/groups/developer/T697a32b688807e56/cve-2026-102916-18491-bhyve-rep-prefix-instr-emulation-fumbles-flags","label":"0ca53633-f0b5-4853-ba72-e0a2e62000d0"}],"tags":["nvd"],"ingestedAt":"2026-10-09T16:02:33.373Z","slug":"CVE-2026-102916","body":"## Overview\n\nA 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.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}