Samsung has updated the Galaxy S6 series and Galaxy Note 5, years after official support for the devices ended. The four handsets remain on Android 7.0 Nougat and the September 2018 security patch, but Samsung claims to have optimised security-related code in some regard.
https://www.notebookcheck.net/The-Samsung-Galaxy-S6-S6-Edge-S6-Edge-S6-Edge-and-Galaxy-Note-5-receive-new-updates.505091.0.html