The Bluetooth Low Energy Secure Manager Protocol (SMP) implementation on Telink Semiconductor BLE SDK versions before November 2019 for TLSR8x5x through 3.4.0, TLSR823x through 1.3.0, and TLSR826x through 3.3 devices accepts a pairing request with a key size greater than 16 bytes, allowing an attacker in radio range to cause a buffer overflow and denial of service (crash) via crafted packets.