gnome-screensaver 2.14.3, 2.22.2, 2.27.x, 2.28.0, and 2.28.3, when the X configuration enables the extend screen option, allows physically proximate attackers to bypass screen locking, access an unattended workstation, and view half of the GNOME desktop by attaching an external monitor.
https://exchange.xforce.ibmcloud.com/vulnerabilities/56366
https://bugzilla.redhat.com/show_bug.cgi?id=557525
https://bugzilla.gnome.org/show_bug.cgi?id=593616
http://www.securityfocus.com/bid/38254
http://www.mandriva.com/security/advisories?name=MDVSA-2011:093
http://security-tracker.debian.org/tracker/CVE-2010-0285
http://git.gnome.org/browse/gnome-screensaver/commit/?id=2f597ea9f1f363277fd4dfc109fa41bbc6225aca