RPM of new major version of the Mozilla Foundation browser are available in the remi repository for fedora 14 and enterprise linux 6 (RHEL, CentOS, ...).
To read: Mozilla Firefox Release Notes Installation : yum --enablerepo=remi update firefox Notice : this RPM is close of firefox 12 one from fedora 15/16/17. This package needs xulrunner12 which install beside default one. RPM are available for fedora 14 and, for enterprise linux 6.... Lire Firefox 12