Archlinux has 67.0.3 already. Some mirrors are still not updated with it, but the one on kernel.org is. Just put that mirror on the top of the /etc/pacman.d/mirrorlist file before running sudo pacman -Sy firefox.
Gentoo also seems to have updated firefox-bin (and possibly www-client/firefox too?)...I ran an emerge update a few minutes ago and saw it install the firefox update
> A type confusion vulnerability can occur when manipulating JavaScript objects due to issues in Array.pop. This can allow for an exploitable crash. We are aware of targeted attacks in the wild abusing this flaw.