An issue was discovered on Moxa AWK-3121 1.14 devices. It provides alert functionality so that an administrator can send emails to his/her account when there are changes to the device's network. However, the same functionality allows an attacker to execute commands on the device. The POST parameters "to1,to2,to3,to4" are all susceptible to buffer overflow. By crafting a packet that contains a string of 678 characters, it is possible for an attacker to execute the attack.
https://seclists.org/bugtraq/2019/Jun/8
https://github.com/samuelhuntley/Moxa_AWK_1121/blob/master/Moxa_AWK_1121