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

> A privileged guest user can panic the illumos bhyve host by triggering a reachable assertion during REP string instruction emulation against MMIO regions.

- **Severity:** Medium 6.8 (`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`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 9 Oct 2026
- **Updated:** 9 Oct 2026
- **Also known as:** GHSA-rx9m-cwq2-hf3w

## What is CVE-2026-102916?

CVE-2026-102916 is a medium-severity denial of service vulnerability in OmniOS, published on 9 Oct 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### 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.

Weakness: CWE-617 (Reachable Assertion)

## Which versions are affected by CVE-2026-102916?


## How do I fix CVE-2026-102916?

No fix has been published for CVE-2026-102916 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-102916 being exploited?

There is no known exploitation of CVE-2026-102916 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-102916 and fix it if it is affected.

What it is: CVE-2026-102916 is a medium-severity denial of service vulnerability in OmniOS, published on 9 Oct 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-102916 in the wild and no public exploit code.

Affected product: OmniOS. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-102916/ (Markdown: https://insights.sbomify.com/CVE-2026-102916/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-102916
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-102916
- OSV: https://osv.dev/vulnerability/CVE-2026-102916

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-102916/
Summaries are generated and may contain mistakes; the official description above is the record.