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Fencer Vulns
high 7.8

CVE-2026-46655 json

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

published 2026-09-18 51 d ago modified 2026-09-30 39 d ago also EUVD-2026-83179

cvss
7.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 7%
public exploits
0
none known

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[*].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.

Patch / fix

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-46655 updated cvss 7.8

virtio-win: viosock.sys: integer overflow in VIOSockSelect leads to heap-based buffer overflow

  • Red Hat Enterprise Linux 8 virtio-win
    affected: workaround, no fix planned “Will not fix”
  • Red Hat Enterprise Linux AppStream (v. 9) virtio-win 1.9.58-0.el9_4, virtio-win 1.9.61-0.el9_8
    fixed: vendor fix RHBA-2026:56986
  • Red Hat Enterprise Linux AppStream (v. 10) virtio-win 1.9.58-0.el10_2
    fixed: vendor fix RHBA-2026:43594
  • Red Hat Enterprise Linux AppStream E4S (v.9.2) virtio-win 1.9.58-0.el9_2
    fixed: vendor fix RHBA-2026:65127
  • Red Hat Enterprise Linux AppStream EUS (v. 10.0) virtio-win 1.9.58-0.el10_0
    fixed: vendor fix RHBA-2026:65134
  • Red Hat Enterprise Linux AppStream EUS (v.9.6) virtio-win 1.9.58-0.el9_6
    fixed: vendor fix RHBA-2026:65128
  • Red Hat OpenShift Virtualization 4 container-native-virtualization/virtio-win
    not affected: component not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
total
Assessed
46 d ago

Exploit prediction

0.18% chance of exploitation in the next 30 days, higher than 7% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/virtio-win/kvm-guest-drivers-windows/security/advisories/GHSA-qrhp-4mhp-hjwh referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected products

  • virtio-win kvm-guest-drivers-windows

Classification

Weakness
  • CWE-122 Heap-based Buffer Overflow
  • CWE-190 Integer Overflow or Wraparound

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.