An issue was discovered on Zyxel GS1900 devices with firmware before 2.50(AAHH.0)C0. Due to lack of input validation in the cmd_sys_traceroute_exec(), cmd_sys_arp_clear(), and cmd_sys_ping_exec() functions in the libclicmd.so library contained in the firmware, an attacker could leverage these functions to call system() and execute arbitrary commands on the switches. (Note that these functions are currently not called in this version of the firmware, however an attacker could use other vulnerabilities to finally use these vulnerabilities to gain code execution.)