Bluetooth in Android 4.x before 4.4.4, 5.0.x before 5.0.2, 5.1.x before 5.1.1, and 6.x before 2016-08-01 allows attackers to cause a denial of service (loss of Bluetooth 911 functionality) via a crafted application that sends a signal to a Bluetooth process, aka internal bug 28885210.