NetComm NF20MESH routers running firmware R6B031 and earlier contain an authenticated remote code execution vulnerability that allows authenticated attackers to execute arbitrary commands as root by injecting shell metacharacters into the username JSON parameter processed by the dalStorage_addUserAccount function. Attackers can exploit the unsafe concatenation of user-supplied input into a shell command string passed to rut_doSystemAction without sanitization to achieve full root-level command execution on the underlying operating system.