---
title: "CVE-2026-46655: virtio-win - Privilege Escalation"
description: "virtio-win from mm210 to mm320 contains a buffer overflow in the Viosock driver caused by improper bounds checking of fd_count in IOCTL_SELECT requests, letting low-privilege local attackers escalate privileges in Windows guests, exploit requires local access."
url: https://panop.io/threat-heartbeat/CVE-2026-46655/
---

# CVE-2026-46655 virtio-win - Privilege Escalation

virtio-win from mm210 to mm320 contains a buffer overflow in the Viosock driver caused by improper bounds checking of fd\_count in IOCTL\_SELECT requests, letting low-privilege local attackers escalate privileges in Windows guests, exploit requires local access.

CVSS base score 7.8 /10

High

CISA KEV

Not listed

Public exploit

None known

Authentication

Required

EPSS

0.18% chance of exploitation in 30 days

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-46655)

## Details

Type

Privilege Escalation

Impact

Privilege Escalation

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Published

18 September 2026

Updated

15 October 2026

Weakness

[CWE-122](https://cwe.mitre.org/data/definitions/122.html)

## Vendor fix

Update to version mm320 or later.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

## References

- [https://nvd.nist.gov/vuln/detail/CVE-2026-46655](https://nvd.nist.gov/vuln/detail/CVE-2026-46655)
- [https://github.com/virtio-win/kvm-guest-drivers-windows/commit/c6bef93d7909584bbda4e5c87603ea175825f342](https://github.com/virtio-win/kvm-guest-drivers-windows/commit/c6bef93d7909584bbda4e5c87603ea175825f342)
- [https://github.com/virtio-win/kvm-guest-drivers-windows/pull/1568](https://github.com/virtio-win/kvm-guest-drivers-windows/pull/1568)
- [https://github.com/virtio-win/kvm-guest-drivers-windows/releases/tag/mm320](https://github.com/virtio-win/kvm-guest-drivers-windows/releases/tag/mm320)
- [https://github.com/virtio-win/kvm-guest-drivers-windows/security/advisories/GHSA-qrhp-4mhp-hjwh](https://github.com/virtio-win/kvm-guest-drivers-windows/security/advisories/GHSA-qrhp-4mhp-hjwh)

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## What this record can't tell you

- Whether you run the affected software, and where
- Whether an attacker can actually reach and exploit it
- The misconfigurations that never get a CVE number
- What it would cost the business, ranked into what to fix first

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