> BLE 4.2 adds 'Secure Connections'. This is apparently also broken and what's more it was broken in 2008 when the same pairing method was used in Bluetooth 2.1!! It doesn't totally break pairing - only the passkey entry method - and you only learn the passkey, not the LTK. But it does allow an attacker to perform a MitM attack if the passkey isn't changed for every pairing attempt.

https://devzone.nordicsemi.com/f/nordic-q-a/14481/secure-ble...