T-Mobile Samsung Galaxy S5 updated to Android 5.1.1; various models receive Stagefright fix
The Stagefright exploit is serious stuff. You could find that someone has sent you a malicious MMS which in some cases doesn't even need to be opened for you to lose control of your camera, microphones, and personal data. And because it is believed that Stagefright has a genesis from insecure code found in the Stagefright multimedia library in use since Froyo, as many as 95% of active Android devices could be vulnerable.
Besides the update to the Galaxy S5, T-Mobile is sending out fixes to the Samsung Galaxy Note 4, and the Samsung Galaxy Note Edge. Those updates are for messaging security improvements and can be downloaded OTA or via Samsung Kies. We should see other models, such as the Samsung Galaxy S6 and Samsung Galaxy S6 edge soon receive the same patch to close the Stagefright exploit for those models.
Verizon also updated its version of the Samsung Galaxy Note 4 today to prevent Stagefright from affecting its subscribers who own Samsung's high-end phablet. The baseband version of the update is N910VVRU2BOG5. The baseband versions of the T-Mobile updates are G900TUVU1FOG6 (Galaxy S5), N915TUVU1BOG2 (Galaxy Note Edge) and N910TUVU1COG2 (Galaxy Note 4).
source: XDA, T-Mobile (1), (2), (3) via AndroidCentral