I think thta KDE's file should have 600 too like the origin - even if /tmp/kde-<user> is set to 700, or ? : $ ls -l /tmp/kde-tfoerste/xauth-1000-_0 ~/.Xauthority -rw------- 1 tfoerste users 207 Jan 4 22:13 /home/tfoerste/.Xauthority -rw-r--r-- 1 tfoerste users 207 Jan 4 22:13 /tmp/kde-tfoerste/xauth-1000-_0 $ md5sum /tmp/kde-tfoerste/xauth-1000-_0 ~/.Xauthority b5bb19323d430c6ddae705ae6c43fcbf /tmp/kde-tfoerste/xauth-1000-_0 b5bb19323d430c6ddae705ae6c43fcbf /home/tfoerste/.Xauthority Reproducible: Always
i have no clue what is creating /tmp/kde-tfoerste/xauth-1000-_0, but it certainly isn't kdm itself.
(In reply to Oswald Buddenhagen from comment #1) > i have no clue what is creating /tmp/kde-tfoerste/xauth-1000-_0, but it > certainly isn't kdm itself. https://github.com/KDE/kdelibs/commit/6891c6f7342501601e74b8c3ed7949850eb13399 https://bugs.kde.org/show_bug.cgi?id=75492 See also bug 358593.
KDM is unmaintained and not used in KDE Plasma 5. SDDM is the login manager used in KDE Plasma 5. If you still have this same issue with SDDM, please file an issue on the SDDM bugtracker (after doing a search for existing issues first!): https://github.com/sddm/sddm/issues/