XScreenSaver 4.10, when using a remote directory service for credentials, does not properly handle the results from the getpwuid function in drivers/lock.c when there is no network connectivity, which causes XScreenSaver to crash and unlock the screen and allows local users to bypass authentication.

Xscreensaver before 4.15 creates temporary files insecurely in (1) driver/passwd-kerberos.c, (2) driver/xscreensaver-getimage-video, (3) driver/xscreensaver.kss.in, and the (4) vidwhacker and (5) webcollage screensavers, which allows local users to overwrite arbitrary files via a symlink attack.