The LB-Link routers, including the BL-AC2100_AZ3 V1.0.4, BL-WR4000 v2.5.0, BL-WR9000_AE4 v2.4.9, BL-AC1900_AZ2 v1.0.2, BL-X26_AC8 v1.2.8, and BL-LTE300_DA4 V1.2.3 models, are vulnerable to unauthorized command injection. Attackers can exploit this vulnerability by accessing the /goform/set_serial_cfg interface to gain the highest level of device privileges without authorization, enabling them to remotely execute malicious commands.