Log in Start free

Vulnerability · Published Sep 18, 2026 · Assigned by GitHub_M

CVE-2026-46655virtio-win: Integer overflow causing a heap overflow in Viosock driver

High 7.8

In plain English

A high-severity heap buffer overflow in kvm-guest-drivers-windows from virtio-win. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 7% of all known vulnerabilities).

Severity (CVSS 3.1)7.8High
Exploit odds (30 days)0.2%top 92.9% of all CVEs
Exploited in the wildNo reportsCISA SSVC: poc
Attack toolingNoneno public tooling known

Official description

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.

Affected products (as reported)

VendorProductVersions
virtio-win kvm-guest-drivers-windows >= mm210, < mm320

Weakness: CWE-122, CWE-190 · Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

References