14 DAY TRIAL // Canonical published details about a number of Libav vulnerabilities in its Ubuntu 13.10, Ubuntu 12.10, and Ubuntu 12.04 LTS operating systems.
According to the company, Libav could have been made to crash or run programs as the user's login if it opened a specially crafted file.
It has been discovered that Libav incorrectly handled certain malformed media files. If a user was tricked into opening a crafted media file, an attacker could have caused a denial of service via application crash, or possibly execute arbitrary code with the privileges of the user invoking the program.
For a more detailed description of the problems, you can see Canonical's security notification.
The flaws can be fixed if you upgrade your system(s) to the latest libavformat53 and libavcodec53 packages specific to each distribution. To apply the patch, run the Update Manager application.
In general, a standard system update will make all the necessary changes. A system restart is not necessary.