It will depend what version of Java you are using, as there is a config in Firefox 43 that blocks all plugins that have been deemed a priority 1 vulnerability based on these release dates (it does not matter the Firefox version) this about:config
It will depend what version of Java you are using, as there is a config in Firefox 43 that blocks all plugins that have been deemed a priority 1 vulnerability based on these release dates (it does not matter the Firefox version) this about:config