MQTT before 3.4.6 and 4.0.x before 4.0.5 allows specifically crafted MQTT packets to crash the application, making a DoS attack feasible with very little bandwidth.
CVSS 3.0HIGH 7.5·Network·No auth·No interaction·EPSS 0.0242·Published 2018-05-31·Fixed in 3.4.6, 4.0.5CWE-400