Look at perlsec, especially the section Laundering and Detecting Tainted Data.

As far as alternatives to CGI.pm, I don't know of one, at least for basic CGI scripting (which I take it is where you are at the moment). But why do you want an alternative? Is there some reason why you don't want to use CGI.pm? It's one of the all-time best modules out there. Just be glad it exists, and go for it.