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/86156/sa38532.txt
Source: https://packetstormsecurity.com/files/86156/Secunia-Security-Advisory-38532.html