On December 12, Canonical published in a security notice details about an APT vulnerability for its Ubuntu 12.10 (Quantal Quetzal), Ubuntu 12.04 (Precise Pangolin), and Ubuntu 11.10 (Oneiric Ocelot) operating systems.
According to Canonical, APT could have made to expose sensitive information.
It was discovered that APT set inappropriate permissions on the term.log file. A local attacker could have used this flaw to possibly obtain sensitive information from one the three operating systems mentioned above.
For a more detailed description of the security problems, you can visit Canonical's security notification.
Users can simply fix the security flaws by upgrading the operating systems to the latest gimp package, specific to each distribution.
A normal system update, executed with the Update Manager, will implement all the necessary changes. A complete system restart is not necessary.