gnome-screensaver would allow unintended access to the user session.
It was discovered that gnome-screensaver did not start automatically after logging in. This may result in the screen not being automatically locked after the inactivity timeout is reached, permitting an attacker with physical access to gain access to an unlocked session.
12 February 2013
A security issue affects these releases of Ubuntu and its derivatives:
gnome-screensaver would allow unintended access to the user session.
It was discovered that gnome-screensaver did not start automatically after logging in. This may result in the screen not being automatically locked after the inactivity timeout is reached, permitting an attacker with physical access to gain access to an unlocked session.
The problem can be corrected by updating your system to the following package versions:
To update your system, please follow these instructions: https://wiki.ubuntu.com/Security/Upgrades.
After a standard system update you need to restart your session to make all the necessary changes.
Vulmon