The Edimax BR-6478AC router firmware version 1.23 contains a stack-based buffer overflow vulnerability in the POST request handler function formWanTcpipSetup. Specifically, the vulnerability arises from unsafe handling of the pppUserName parameter, which can be manipulated remotely to overflow the stack buffer. This vulnerability has a CVSS 4.0 base score of 8.7, indicating high severity with network attack vector, low attack complexity, no privileges required, no user interaction, and high impact on confidentiality, integrity, and availability. No vendor advisory or patch information is currently available, and the vulnerability is publicly known with an exploit accessible.

Successful exploitation of this vulnerability can lead to remote code execution or denial of service on the affected device due to the stack-based buffer overflow. The attacker can potentially compromise the router's confidentiality, integrity, and availability. The vulnerability requires no privileges or user interaction and can be triggered remotely over the network.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is released, it is recommended to restrict network access to the affected device's management interfaces, especially from untrusted networks. Monitor vendor communications for updates and apply patches promptly once available.