The Bluetooth Low Energy Secure Manager Protocol (SMP) implementation in Texas Instruments SimpleLink SIMPLELINK-CC2640R2-SDK through 2.2.3 allows the Diffie-Hellman check during the Secure Connection pairing to be skipped if the Link Layer encryption setup is performed earlier. An attacker in radio range can achieve arbitrary read/write access to protected GATT service data, cause a denial of service, or possibly control a device's function by establishing an encrypted session with an unauthenticated Long Term Key (LTK).