Clemens Fries reported that, when using Cinnamon, it was possible to bypass the screensaver lock:
http://seclists.org/oss-sec/2014/q1/327
An attacker with physical access to the machine could use this flaw to take over the locked desktop session.
A patch is currently not yet available.
mintinstall (aka Software Manager) 7.9.9 for Linux Mint allows code execution if a REVIEWSCACHE file is controlled by an attacker, because an unpickle occurs. This is resolved in 8.0.0 and backports.