https://bugzilla.mozilla.org/show_bug.cgi?id=1544386 I find it really gross that they do not allow others to access it. This behavior damages the forks.
I say used to because I notice that the security issues fixed in Firefox 66.0 (released in March according to the release notes) still appear to be private. I suspect the internal people that cared about it have left, and their process is now broken. Somebody might read this thread and poke people to open access, but it would have to be done as an exceptional step (given that it hasn't been the first time I've noticed this happening).