An issue was discovered in SDDM before 0.19.0. It incorrectly starts the X server in a way that - for a short time period - allows local unprivileged users to create a connection to the X server without providing proper authentication. A local attacker can thus access X server display contents and, for example, intercept keystrokes or access the clipboard. This is caused by a race condition during Xauthority file creation.
lists.opensuse.org/opensuse-security-announce/2020-11/msg00031.html
bugzilla.suse.com/show_bug.cgi?id=CVE-2020-28049
github.com/sddm/sddm/blob/v0.19.0/ChangeLog
github.com/sddm/sddm/releases
lists.debian.org/debian-lts-announce/2020/11/msg00009.html
lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/GT3EX5NSQJJAKY63ENSMEDX6NYZLYY3S/
security.gentoo.org/glsa/202402-02
www.debian.org/security/2020/dsa-4783