Bluetooth® Pairing in Bluetooth Core Specification v1.0B through v5.3 may permit an unauthenticated MITM to acquire credentials with two pairing devices via adjacent access when at least one device supports BR/EDR Secure Connections pairing and the other BR/EDR Legacy PIN code pairing if the MITM negotiates BR/EDR Secure Simple Pairing in Secure Connections mode using the Passkey association model with the pairing Initiator and BR/EDR Legacy PIN code pairing with the pairing Responder and brute forces the Passkey entered by the user into the Responder as a 6-digit PIN code. The MITM attacker can use the identified PIN code value as the Passkey value to complete authentication with the Initiator via Bluetooth pairing method confusion.
