A flaw was found in the way xserver memory was not properly initialized. This could leak parts of server memory to the X client. In cases where Xorg server runs with elevated privileges, this could result in possible ASLR bypass. Xorg-server before version 1.20.9 is vulnerable.
https://www.openwall.com/lists/oss-security/2020/07/31/2
https://www.debian.org/security/2020/dsa-4758
https://usn.ubuntu.com/4488-2/
https://usn.ubuntu.com/4488-1/
https://security.gentoo.org/glsa/202012-01
https://lists.x.org/archives/xorg-announce/2020-July/003051.html
https://lists.debian.org/debian-lts-announce/2020/08/msg00057.html
https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2020-14347
http://lists.opensuse.org/opensuse-security-announce/2020-08/msg00075.html
http://lists.opensuse.org/opensuse-security-announce/2020-08/msg00066.html