Bug 2401209 (CVE-2025-11234)

Summary: CVE-2025-11234 qemu-kvm: VNC WebSocket handshake use-after-free
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: ailan, ddepaula, jen, jferlan, jmaloy, kkiwi, knoel, mrezanin, mst, nilal, pbonzini, ymankad
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
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Doc Text:
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.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On: 2401210, 2401212    
Bug Blocks:    

Description OSIDB Bzimport 2025-10-03 09:48:17 UTC 
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 flaw 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.

Reported-by:
Grant Millar | Cylo <rid>

Upstream patch:
https://lists.nongnu.org/archive/html/qemu-devel/2025-09/msg06566.html