CVE-2023-5574

A use-after-free flaw was found in xorg-x11-server-Xvfb. This issue occurs in Xvfb with a very specific and legacy configuration (a multi-screen setup with multiple protocol screens, also known as Zaphod mode). If the pointer is warped from a screen 1 to a screen 0, a use-after-free issue may be triggered during shutdown or reset of the Xvfb server, allowing for possible escalation of privileges or denial of service.

Mitigation

Starting Xvfb with the -noreset command line option limits the use-after-free from being triggered only at the Xvfb server shutdown. Also, do not start Xvfb as root.