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VulnerabilityPublished Updated

CVE-2026-46655: virtio-win kvm-guest-drivers-windows · Heap-based Buffer Overflow

Affects virtio-win kvm-guest-drivers-windowsSource CVE Database V5

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Not known to be exploited · CVSS 7.8 High : upgrade to mm320 soon.

Data as of 2 Nov 2026, 10:58 UTC

CVSS 3.1 base score
7.8High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.1% chance of exploitation in 30 days – higher than 6% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in mm320
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 18 Sep 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2 Nov 2026.

What to do

Upgrade kvm-guest-drivers-windows and virtio-win/kvm-guest-drivers-windows to mm320.

Affected software

ProductAffectedFixed in
virtio-winkvm-guest-drivers-windowsAffected
  • >=mm210 <mm320
Fixed in
  • mm320
GitHubvirtio-win/kvm-guest-drivers-windowspkg:github/virtio-win/kvm-guest-drivers-windowsOther threatsAffected
  • >=mm210 <mm320
Fixed in
  • mm320

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

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 temporary workaround is indicated in the available data.

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.

References

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