---
id: CVE-2026-46655
title: virtio-win provides Windows paravirtualized drivers for QEMU and KVM
summary: >-
  virtio-win provides Windows paravirtualized drivers for QEMU and KVM. From
  mm210 until mm320, the Viosock driver permits a low-privilege local process to
  submit an IOCTL_SELECT request with attacker-controlled
  VIRTIO_VSOCK_SELECT.Fdss[*]…
severity: high
cvss: 7.8
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-122
  - CWE-190
vendor: virtio-win
product: kvm-guest-drivers-windows
affected:
  - 'kvm-guest-drivers-windows >= mm210, < mm320'
published: '2026-09-18'
updated: '2026-09-23'
sourceUpdated: '2026-09-23T20:17:10.863'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-46655'
references:
  - url: >-
      https://github.com/virtio-win/kvm-guest-drivers-windows/commit/c6bef93d7909584bbda4e5c87603ea175825f342
    label: security-advisories@github.com
  - url: 'https://github.com/virtio-win/kvm-guest-drivers-windows/pull/1568'
    label: security-advisories@github.com
  - url: 'https://github.com/virtio-win/kvm-guest-drivers-windows/releases/tag/mm320'
    label: security-advisories@github.com
  - url: >-
      https://github.com/virtio-win/kvm-guest-drivers-windows/security/advisories/GHSA-qrhp-4mhp-hjwh
    label: security-advisories@github.com
  - url: >-
      https://github.com/virtio-win/kvm-guest-drivers-windows/security/advisories/GHSA-qrhp-4mhp-hjwh
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-46655.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-46655'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2489170'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-46655'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-46655'
tags:
  - nvd
  - cve.org
  - exploit-available
  - csaf
  - vex
  - red-hat
exploitAvailable: true
ssvc:
  exploitation: poc
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-09-23T19:14:57.635548Z'
epss: 0.0018
epssPercentile: 0.06741
ingestedAt: '2026-09-18T17:46:41.519Z'
---

## Overview

virtio-win provides Windows paravirtualized drivers for QEMU and KVM. From mm210 until mm320, the Viosock driver permits a low-privilege local process to submit an IOCTL_SELECT request with attacker-controlled VIRTIO_VSOCK_SELECT.Fdss[*].fd_count values that overflow the 32-bit sum used by VIOSockSelect for bounds checking. The wrapped sum can pass the FD_SETSIZE check even though an individual descriptor count is much larger than the expected limit. VIOSockSelectCopyFds then iterates using the unchecked count and writes beyond the allocated pPkt->Fds array in the NonPagedPool kernel heap. Successful exploitation can corrupt kernel memory and enable privilege escalation in a Windows guest running the driver. This issue is fixed in mm320.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Vendor advisories

- **Red Hat VEX** · Important · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9 · no fix planned: Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9 · updated 2026-09-22 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-46655.json)