driver/subprocs.c in XScreenSaver before 5.34 does not properly perform an internal consistency check, which allows physically proximate attackers to bypass the lock screen by hot swapping monitors.
lists.opensuse.org/opensuse-updates/2015-11/msg00102.html
www.debian.org/security/2016/dsa-3438
www.openwall.com/lists/oss-security/2015/10/24/2
www.openwall.com/lists/oss-security/2015/10/25/1
www.openwall.com/lists/oss-security/2015/10/29/12
www.oracle.com/technetwork/topics/security/bulletinjul2016-3090568.html
www.securitytracker.com/id/1034052
www.ubuntu.com/usn/USN-2789-1
twitter.com/Thaolia/status/656823859304398848
www.jwz.org/blog/2015/10/xscreensaver-5-34/