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.
References10
- access.redhat.com/errata/RHSA-2025:23228
- access.redhat.com/errata/RHSA-2026:0326
- access.redhat.com/errata/RHSA-2026:0332
- access.redhat.com/errata/RHSA-2026:0702
- access.redhat.com/errata/RHSA-2026:1831
- access.redhat.com/errata/RHSA-2026:18772
- access.redhat.com/errata/RHSA-2026:22147
- access.redhat.com/errata/RHSA-2026:3077
- access.redhat.com/errata/RHSA-2026:3165
- access.redhat.com/errata/RHSA-2026:5578
Metrics
- CVSS 3.1
-
7.5
HIGH
Score source: CNA
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - EPSS — exploit probability
- 1% percentile: 59 · as of 9 November 2026
- CWE
- CWE-416
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.