The latest version of Firefox can be downloaded from Softpedia
On November 21, Canonical published details about Firefox vulnerabilities for its Ubuntu 12.10, Ubuntu 12.04 LTS, Ubuntu 11.10, and Ubuntu 10.04 LTS operating systems, providing a much needed update to version 17.0.According to Canonical, multiple security issues were fixed in Mozilla Firefox. An attacker could have used exploits to cause a denial of service via application crash, could have executed arbitrary code as the user invoking Firefox, or could have stolen confidential data.
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 Firefox 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.
Alternatively, you can download Mozilla Firefox 17.0 right now from Softpedia.