Use-after-free in X.org Server and Xwayland - CVE-2026-34001
Published: April 14, 2026
Vulnerability identifier: #VU125989
CSH Severity: Low
CVSS v4.0: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear
CVE-ID: CVE-2026-34001
CWE-ID: CWE-416
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vendor: X.org
Affected software:
X.org Server
Xwayland
X.org Server
Xwayland
Detailed vulnerability description
The vulnerability allows a local user to cause a denial of service.
The vulnerability exists due to a use-after-free in miSyncTriggerFence() when walking the list of fences to trigger. A local user can trigger fence processing to cause a denial of service.
The issue occurs because freeing the await resource removes subsequent trigger entries from the list during iteration.
How to mitigate CVE-2026-34001
Install security update from vendor's website.