Tenda AC18 Router through V15.03.05.05_EN and through V15.03.05.19(6318) CN devices could cause a remote code execution due to incorrect authentication handling of vulnerable logincheck() function in /usr/lib/lua/ngx_authserver/ngx_wdas.lua file if the administrator UI Interface is set to "radius".
CWE-287 - Improper Authentication
Improper (or broken) authentication attacks are widespread, and have accounted for many of the worst data breaches in recent years. Improper authentication attacks are a class of vulnerabilities where an attacker impersonates a legitimate user by exploiting weaknesses in either session management or credential management to gain access to the user’s account. This can result in disclosure of sensitive information, and can lead to system compromise, theft, identity theft, and fraud.