The build of Firefox included with the images and in the fml13v03 repository is very old, having gone EOL over a year ago. The [Mozilla team PPA](https://launchpad.net/~mozillateam/+archive/ubuntu/ppa) contains up-to-date builds of both Firefox and firefox-ESR.
The build of Firefox included with the images and in the fml13v03 repository is very old, having gone EOL over a year ago.
The Mozilla team PPA contains up-to-date builds of both Firefox and firefox-ESR.