A vulnerability that is trivial to exploit allows privilege escalation to root level on Linux and BSD distributions using X.Org server. The flaw is now identified as CVE-2018-14665 (credited to security researcher Narendra Shinde) It has been present in xorg-server for two years, since version 1.19.0. The OpenBSD project released version 6.4 of the OS, affected by the bug, on October 18. The bug could have been avoided in the release of the new OpenBSD OS.
Source: https://www.bleepingcomputer.com/news/security/trivial-bug-in-xorg-gives-root-permission-on-linux-and-bsd-systems/