Nov 4th was the last version release, I havent had any issues with my furryfox since the last time I updated, which was... maybe the 3rd nov? so unless its specifically the new version?
so if you havent used it for a few days maybe? I actually dont know how non-rolling distros do it for browsers tbh, tho I think unstable will be pretty much up to date. Browsers are basically the only real vulnerability thing to keep up to date