During BLE secure pairing the implementation responds to DHKeyCheckSend message with MacKey,Na and Nb set to zero.

the implementation fails to properly check the confirmation value. In the specification it is clearly stated - If this (conformation value) check fails, it indicates that the initiating device has not confirmed the pairing, and the protocol must be aborted. However, this implementation responds if the key values are set to zero.

This issue happens because the central device is sending the pairing messages through the SMP in the wrong order.