CVE-2025-11234 HIGH

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

Vendor Red Hat
Product Red Hat Enterprise Linux 6
Weakness CWE-416
Published October 3, 2025
Last update June 1, 2026

CVSS base score

7.5/10
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Confidentiality None
Integrity None

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

What the vulnerability does

01Description

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.

Key dates

02Disclosure timeline

October 3, 2025 CVE published
June 1, 2026 Record updated