After Verizon, now T-Mobile and Sprint are pushing a new software update for the Galaxy Note 8 and the Galaxy S9/S9+. The latest update brings the December 2018 security patch, and providing fixes to 40 Samsung Vulnerabilities and Exposures (SVE) items.
The Galaxy Note 8 is receiving this update as build version N950USQS5CRK1. While the software version is G960USQS3BRK2 and G965USQS3BRK2 for the Galaxy S9 and S9+ respectively.
If you want to check this update manually, head into Settings > Software update > Download updates manually or you can simply wait till the update automatically appears on your phone.