AT&T has started pushing out a new update to Samsung Galaxy S6 active units on its network. Weighing in at just over 14MB and carrying a build number of G890AUCS5CPK4, the update brings Android security fixes for the month of December.
Aside from the December security patch, nothing else is included in the update - at least that's what the official change-log suggests.
As is usually the case with OTA roll outs, it may take time for the update notification to pop up on your device's screen. Meanwhile, if you feel impatient, you can manually check for the update by heading to your handset's Settings menu.