Description of problem: firefox-24 is not available as an update testing for fedora 18 firefox-24 is available for fedora 19
It's here: https://admin.fedoraproject.org/updates/FEDORA-2013-17047/xulrunner-24.0-2.fc18,firefox-24.0-1.fc18 Unfortunately the update does not have enough karma to go. You can download the packages from koji.
Already there - https://admin.fedoraproject.org/updates/FEDORA-2013-17047/xulrunner-24.0-2.fc18,firefox-24.0-1.fc18