Multiple security issues have been found in the Mozilla Firefox web browser: Multiple memory safety errors, buffer overflows and other implementation errors may lead to the execution of arbitrary code or spoofing. Wait, Firefox? No more references to Iceweasel? That"s right, Debian no longer applies a custom branding. Please see these links for further information: https://glandium.org/blog/?p=3622 https://en.wikipedia.org/wiki/Mozilla_software_rebranded_by_Debian Debian follows the extended support releases of Firefox. Support for the 38.x series has ended, so starting with this update we"re now following the 45.x releases and this update to the next ESR is also the point where we reapply the original branding. Transition packages for the iceweasel packages are provided which automatically upgrade to the new version. Since new binary packages need to be installed, make sure to allow that in your upgrade procedure .