Possible Fix for Exploit that Allows You to Play Netgames with Unmatching Wad Lists

I made an untested fix that I need help testing for the exploit that allows you to play netgames with wads that don't match the server so that hosts don't have to worry about players having wads they don't want on their server to be enabled. The problem is that I don't know how to do this exploit, but someone that I saw on Spectrum's server knows how to do this exploit which is why it is untested.