This latest version of Firefox comes with a lot of security fixes
On January 8, 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 18.0.According to Canonical, multiple security issues were fixed in Mozilla Firefox. For example, an attacker could have used certain exploits to cause a denial of service via application crash, or to potentially execute code with the privileges of the user invoking Firefox.
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 18.0 right now from Softpedia.