From gbhackers.com
Researchers discovered a severe privilege escalation vulnerability in Bluetooth let unauthenticated attackers intercept and monitor the encryption traffic between two paired devices.
The bug discovered in Bluetooth BR/EDR encryption connection, in which an attacker reduces the encryption key length and perform a brute-force attack to decrypt communications between the devices.
Bluetooth BR/EDR ( Basic Rate/Enhanced Data Rate) is used for low-power short-range communications, and the encrypted connection can be established by pairings the two Bluetooth devices and establish a link key that is used to generate the encryption key.
Here the Key Negotiation of Bluetooth (KNOB) attack comes into play that an attacker can force two Bluetooth devices to use as low as 1 byte of entropy and reduce the key length.