GCVE-110-CERTCC-2018-918987

The encryption key length negotiation process in Bluetooth BR/EDR Core v5.1 and earlier is vulnerable to packet injection by an unauthenticated, adjacent attacker that could result in information disclosure and/or escalation of privileges. This can be achieved using an attack referred to as the Key Negotiation of Bluetooth (KNOB) attack, which is when a third party forces two or more victims to agree on an encryption key with as little as one byte of entropy. Once the entropy is reduced, the attacker can brute-force the encryption key and use it to decrypt communications.