Qemu-kvm: vnc websocket handshake use-after-free
Vulnerability 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.
Impact Analysis
Refer to official advisory for detailed impact metrics.
Remediation
Ensure systems are updated to the latest vendor-supplied patch levels.
Am I Vulnerable?
Launch our assessment wizard to check if your infrastructure is exposed to • CVE-2025-11234
Credits & Attribution
The following person or organization is credited with identifying this vulnerability, as recorded in the NVD database:
- Red Hat would like to thank Grant Millar (Cylo) for reporting this issue.
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/security/cve/CVE-2025-11234
- https://bugzilla.redhat.com/show_bug.cgi?id=2401209
More from Unknown
View All →Affected Vendor
Unknown
View all reports →