{"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":"medium","cwe":["CWE-617"],"published":"2026-10-09","updated":"2026-10-09","sourceUpdated":"2026-10-09T22:16:55.220","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"},{"url":"http://www.openwall.com/lists/oss-security/2026/10/09/19","label":"af854a3a-2127-422b-91ae-364da2661108"}],"tags":["nvd","cve.org"],"ingestedAt":"2026-10-09T16:02:33.373Z","epss":0.00123,"epssPercentile":0.02079,"vendor":"illumos","product":"system/bhyve","affected":["system/bhyve >= e0c0d44e917080841514d0dd031a696c74e8c435 < 696ecf8debceed9dc33937d8c8e111e4aeebfdae","OmniOS >= any < r151054","OmniOS >= r151058 < r151058w","OmniOS >= r151056 < r151056aw","OmniOS >= r151054 < r151054bw"],"cvss":6.8,"cvssVector":"CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H/E:P/AU:Y/R:A/V:C","ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"partial","timestamp":"2026-10-09T16:15:23.994154Z"},"cvssSource":"cna","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":37,"depthScoreParts":{"impact":37.4,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[{"seq":220679,"id":"CVE-2026-102916","ts":1792026553948,"field":"cvss","old":null,"new":"6.8"},{"seq":220678,"id":"CVE-2026-102916","ts":1792026553948,"field":"severity","old":"none","new":"medium"}]}