It's time to update your unlocked Galaxy flagships because a new update has been pushed to Galaxy S9, S9+, Note9, and Note8 that improves the security of these devices.
The latest software update brings December 2018 security patch, providing fixes to 40 Samsung Vulnerabilities and Exposures (SVE) items.
The Build version for the Galaxy S9 and S9+ are G960U1UEU3ARL1/G965 respectively, Galaxy Note 9 as version N960U1UEU1ARL1 and Galaxy Note 8 as N950U1UEU5CRL2.
Apart from other mobile carriers, T-Mobile's Unlocked S9 and S9+ receiving November instead of December security update with build number G960U1UEU3ARK5 and G965U1UEU3ARK5 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 in your phone.
As the Galaxy S8 and S8+ has already received its December security patch on January 1.