Emergency Bulletin: Firefox 0 day in the wild. What to do.
Apparently Firefox team has fixed the issue.
From the same source: Update at 2:32pm PST / 5:32pm EST: Firefox released a fix for this a few minutes ago…
The patch should be available with Firefos 50.0.2.
Updated mirrors still contain Firefox 50.0-1 here. Have to wait a few more hours until 50.0-2 reaches the mirrors.
Firefox 50.0.2-1 is available now:
$ sudo pacman -Syyu ... ==> Software upgrade (new version) : extra/firefox 50.0-1 -> 50.0.2-1 ...