Update:
T-Mobile S6 edge Stagefright fix also rolling out, build G925TUVU2COF8.

Looks like T-Mobile will just silently push the Stagefright fix to Galaxy S6 and (possibly) other Samsung devices without updating the firmware build number.

The carrier, only moments ago, released Stagefright fix for several Nexus devices and it looks like a patch for the vulnerability is also rolling out for the T-Mobile Galaxy S6 G920T with the same firmware build G920TUVU2COF8 which released for the device a week ago for battery-life improvements and various other bug fixes.

The Stagefright fix for your Galaxy S6 should come as a small OTA update of under 50MB size if you already have the OF8 build installed, otherwise the OTA update size will be 631MB if you’re coming from the OCG build OR 102MB if you’re coming from the OF6 build.

To check for the OTA update with Stagefright fix, head on to Settings > About phone > Software updates section and hit the Check for updates button.