Secunia Security Advisory – Ubuntu has issued an update for gnome-screensaver. This fixes a weakness, which can be exploited by malicious people with physical access to bypass certain security restrictions.
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/86968/sa38849.txt
Source: https://packetstormsecurity.com/files/86968/Secunia-Security-Advisory-38849.html