CVE-2026-46655: CWE-122: Heap-based Buffer Overflow in virtio-win kvm-guest-drivers-windows
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.
AI Analysis
Technical Summary
The vulnerability arises from an integer overflow in the Viosock driver's handling of the IOCTL_SELECT request, specifically in the calculation of the sum of fd_count values in VIRTIO_VSOCK_SELECT.Fdss[*]. This overflow allows the sum to wrap and bypass the FD_SETSIZE check, enabling VIOSockSelectCopyFds to write beyond the allocated array in the NonPagedPool kernel heap. This heap-based buffer overflow can corrupt kernel memory and enable privilege escalation in a Windows guest running the affected virtio-win drivers. The flaw affects versions from mm210 up to but excluding mm320, where it has been fixed.
Potential Impact
Exploitation of this vulnerability allows a low-privilege local process within a Windows guest to corrupt kernel memory and escalate privileges. This can lead to full control over the guest operating system, compromising confidentiality, integrity, and availability of the system. The CVSS v3.1 score is 7.8 (high), reflecting the local attack vector with low complexity and no user interaction required, and high impact on confidentiality, integrity, and availability.
Mitigation Recommendations
This vulnerability is fixed in virtio-win version mm320. Users should upgrade to version mm320 or later to remediate this issue. No other mitigation or workaround is indicated in the available data.
CVE-2026-46655: CWE-122: Heap-based Buffer Overflow in virtio-win kvm-guest-drivers-windows
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.
CVSS v3.1
Score 7.8high
Affected software
virtio-win
kvm-guest-drivers-windows
pkg:github/virtio-win/kvm-guest-drivers-windowsRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The vulnerability arises from an integer overflow in the Viosock driver's handling of the IOCTL_SELECT request, specifically in the calculation of the sum of fd_count values in VIRTIO_VSOCK_SELECT.Fdss[*]. This overflow allows the sum to wrap and bypass the FD_SETSIZE check, enabling VIOSockSelectCopyFds to write beyond the allocated array in the NonPagedPool kernel heap. This heap-based buffer overflow can corrupt kernel memory and enable privilege escalation in a Windows guest running the affected virtio-win drivers. The flaw affects versions from mm210 up to but excluding mm320, where it has been fixed.
Potential Impact
Exploitation of this vulnerability allows a low-privilege local process within a Windows guest to corrupt kernel memory and escalate privileges. This can lead to full control over the guest operating system, compromising confidentiality, integrity, and availability of the system. The CVSS v3.1 score is 7.8 (high), reflecting the local attack vector with low complexity and no user interaction required, and high impact on confidentiality, integrity, and availability.
Mitigation Recommendations
This vulnerability is fixed in virtio-win version mm320. Users should upgrade to version mm320 or later to remediate this issue. No other mitigation or workaround is indicated in the available data.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-05-15T20:11:54.585Z
- Cvss Version
- 3.1
- State
- PUBLISHED
Threat ID: 6aad6e9d55bf5e2cf5463696
Added to database: 09/18/2026, 17:02:21 UTC
Last enriched: 09/18/2026, 17:16:39 UTC
Last updated: 09/18/2026, 22:53:06 UTC
Views: 9
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