GNOME Display Manager (gdm) before 3.18.2 allows physically proximate attackers to bypass the lock screen by holding the Escape key.
https://download.gnome.org/sources/gdm/3.18/gdm-3.18.2.news
https://bugzilla.gnome.org/show_bug.cgi?id=758032
https://access.redhat.com/errata/RHSA-2017:2128
http://www.openwall.com/lists/oss-security/2015/11/17/8
http://www.openwall.com/lists/oss-security/2015/11/17/10
http://lists.fedoraproject.org/pipermail/package-announce/2015-November/172328.html