TOTOLINK X5000R v9.1.0cu_2415_B20250515 contains an argument injection vulnerability in the setDiagnosisCfg handler of the /usr/sbin/lighttpd executable. The ip parameter is retrieved via websGetVar and passed to a ping command through CsteSystem without validating if the input starts with a hyphen (-). This allows remote authenticated attackers to inject arbitrary command-line options into the ping utility, potentially leading to a Denial of Service (DoS) by causing excessive resource consumption or prolonged execution.