Ubuntu has issued an update for gnome-screensaver and compiz. This fixes a security issue, which can be exploited by malicious people with physical access to a system to bypass certain security restrictions.

The security issue is caused due to the gnome-screensaver not correctly preventing Compiz from grabbing the input focus. This can be exploited to bypass and disable the screen locking feature via e.g. "alt+tab".

Successful exploitation requires that Compiz is used.

Solution
Apply updated packages.
Further details available to Secunia VIM customers

Provided and/or discovered by
Ubuntu credits Jens Askengren.

Changelog
Further details available to Secunia VIM customers

Original Advisory
https://lists.ubuntu.com/archives/ubuntu-security-announce/2007-October/000616.html
https://lists.ubuntu.com/archives/ubuntu-security-announce/2007-November/000618.html

Deep Links
Links available to Secunia VIM customers