CVE-2026-34001 Xorg: xwayland: x.org x server: use-after-free vulnerability leads to server crash and potential memory corruption
An attacker with X11 access can trigger a use-after-free in X.Org, causing a server crash or potential memory corruption and code execution.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-34001?
CVE-2026-34001 is a high-severity use after free vulnerability in Red Hat Enterprise Linux 10, published on 23 Apr 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
A flaw was found in the X.Org X server. This use-after-free vulnerability occurs in the XSYNC fence triggering logic, specifically within the miSyncTriggerFence() function. An attacker with access to the X11 server can exploit this without user interaction, leading to a server crash and potentially enabling memory corruption. This could result in a denial of service or further compromise of the system.
Weakness: CWE-825
Which versions are affected by CVE-2026-34001?
How do I fix CVE-2026-34001?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-34001 being exploited?
There is no known exploitation of CVE-2026-34001 in the wild and no public exploit code.
Sources
Also known as AZL-84627, AZL-84842, BELL-CVE-2026-34001, DEBIAN-CVE-2026-34001, ECHO-fae0-9195-9d72, GHSA-cjgm-66pw-5r9r and 1 more.