ZTE E8810/E8820/E8822 series routers have an MQTT DoS vulnerability which is caused by the failure of the device to verify the validity of abnormal messages. A remote attacker could connect to the MQTT server and send an MQTT exception message to the specified device which will cause the device to deny service. This affects:<ZXHN E8810 ZXHN E8820 ZXHN E8822><E8810 V1.0.26 E8810 V2.0.1 E8820 V1.1.3L E8820 V2.0.13 E8822 V2.0.13>