A critical security vulnerability has been discovered in Totolink A8000RU router firmware version 7.1cu.643_b20200521. The flaw exists in the setAppFilterCfg function within the /cgi-bin/cstecgi.cgi file, where manipulation of the 'enable' argument leads to OS command injection. This vulnerability can be exploited remotely by attackers. The exploit code has been publicly released, significantly increasing the risk of active exploitation. The vulnerability affects network infrastructure equipment, potentially allowing attackers to execute arbitrary commands on the affected devices.