Following a slew of other Samsung handsets, the Galaxy S6 Active on AT&T is receiving the December security patch through a minor update. The update will bring the security patch level to December 1; that isn't exactly the latest, but these security updates have barely been coming out on time for devices anyway.
The 14.1 MB update – which contains only security fixes – should be showing up on your Galaxy S6 Active shortly. If it doesn't, you can download it from the Settings » About device menu by hitting the Download updates manually button.
