Bluetooth BR/EDR Core Specification <5.2 - Auth Bypass
Legacy pairing and secure-connections pairing authentication in Bluetooth BR/EDR Core Specification v5.2 and earlier may allow an unauthenticated user to complete authentication without pairing credentials via adjacent access. An unauthenticated, adjacent attacker could impersonate a Bluetooth BR/EDR master or slave to pair with a previously paired remote device to successfully complete the authentication procedure without knowing the link key.