CVE-2023-1393

A vulnerability was found in X.Org Server. This flaw occurs if a client explicitly destroys the compositor overlay window (aka COW), where Xserver leaves a dangling pointer to that window in the CompScreen structure, which will later trigger a use-after-free issue. The Overlay Window use-after-free issue can lead to a local privilege escalation vulnerability.

This vulnerability allows local attackers to escalate privileges on affected installations of X.Org Server. An attacker must first obtain the ability to execute low-privileged code on the target system in order to exploit this vulnerability.
The specific flaw exists within the handling of overlay windows. The issue results from the lack of validating the existence of an object prior to performing operations on the object. An attacker can leverage this vulnerability to escalate privileges and execute arbitrary code in the context of root.