14 DAY TRIAL // Canonical has published details in a security notice about Libav vulnerabilities in Ubuntu 13.10 and Ubuntu 12.04 LTS that have been fixed.
This Libav exploit is not a major problem for the Ubuntu systems, but upgrading the system would be a good idea. It's also nice to see that Ubuntu 13.10 hasn't been forgotten, although it's almost close to reaching EOL status.
According to the security notice, “It was discovered that Libav incorrectly handled certain malformed media files. If a user were tricked into opening a crafted media file, an attacker could cause 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. Users should upgrade their Linux distribution in order to correct this issue.
The flaw can be fixed if you upgrade your system(s) to the latest libavformat53 and libavcodec53 packages specific to each distribution. To apply the patch, users can simply run the Update Manager application.
If you don't want to use the Software Updater, you can open a terminal and enter the following commands (you will need to be root):
sudo apt-get dist-upgrade