CVE-2026-46655 virtio-win: Integer overflow causing a heap overflow in Viosock driver
A local attacker can exploit an integer overflow in the Viosock driver to corrupt kernel memory and escalate privileges on Windows guests.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-46655?
CVE-2026-46655 is a high-severity vulnerability in virtio-win kvm-guest-drivers-windows, published on 18 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
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.
Which versions are affected by CVE-2026-46655?
How do I fix CVE-2026-46655?
No fix has been published for CVE-2026-46655 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-46655 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-46655 exists.
Sources
Also known as GHSA-qrhp-4mhp-hjwh.