Description: The remote host is missing an update to gdm announced via advisory USN-1099-1.
Details follow:
Sebastian Krahmer discovered that GDM (GNOME Display Manager) did not properly drop privileges when handling the cache directories used to store users' dmrc and face icon files. This could allow a local attacker to change the ownership of arbitrary files, thereby gaining root privileges.
Solution: The problem can be corrected by upgrading your system to the following package versions:
Ubuntu 9.10: gdm 2.28.1-0ubuntu2.3
Ubuntu 10.04 LTS: gdm 2.30.2.is.2.30.0-0ubuntu5.1
Ubuntu 10.10: gdm 2.30.5-0ubuntu4.1
After a standard system update you need to log out all desktop sessions and restart GDM to make all the necessary changes.