Mozilla has released the new update of Firefox 32.0.3 with many security fixes included. This release was responded by Canonical team and Ubuntu maintainers by putting this new Firefox 32.0.3 in the Official Ubuntu Repositories. So, if you are running Ubuntu 12.04, Ubuntu 14.04 or Ubuntu 14.10 Beta, you can easily install or upgrade to this new Firefox 32.0.3 from your Ubuntu Software Center.
To install or upgrade Firefox on Ubuntu, simply use this command
sudo apt-get update
sudo apt-get install firefox