Vulnerability · Published Oct 9, 2026 · Assigned by illumos

CVE-2026-102916Reachable assertion in illumos bhyve REP string instruction emulation allows guest to panic host

Medium 6.8

In plain English

A medium-severity security flaw in illumos-gate from illumos. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.1% (higher than 2% of all known vulnerabilities).

Severity (CVSS 4.0)6.8Medium

Exploit odds (30 days)0.1%top 97.9% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

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 products (as reported)

Vendor	Product	Versions
illumos	illumos-gate	e0c0d44e917080841514d0dd031a696c74e8c435 – before 696ecf8debceed9dc33937d8c8e111e4aeebfdae
OmniOS	OmniOS	any – before r151054r151058 – before r151058wr151056 – before r151056awr151054 – before r151054bw

Weakness: CWE-617 · Vector: 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

In plain English

Official description

Affected products (as reported)

References