A critical stack-based buffer overflow vulnerability has been identified in Edimax BR-6478AC firmware version 1.23. The vulnerability exists in the formWanTcpipSetup function of the POST Request Handler component, specifically in the /goform/formWanTcpipSetup file. The flaw can be exploited by manipulating the pppUserName argument, leading to a stack-based buffer overflow condition. This vulnerability can be exploited remotely by attackers without requiring authentication. Public exploits are already available, making this a high-priority security concern for organizations using affected devices. The vulnerability poses significant risk as it affects network infrastructure equipment and can be exploited from remote locations.