You might want to check
SecurityFocus. I did a quick search there for "perl" and came up with quite a few examples of how badly written perl had created security holes. Here's a couple:
CVSWeb insecure perl "open" vulnerability
Matt Kruse Calendar Arbitrary Command Execution Vulnerability
Ultimate Bulletin Board Arbitrary Command Execution Vulnerability
There's more under those search results and I'm sure if you searched for stuff like "CGI" and ".pl" etc you'd find hundreds more.
Incidentally, I chose "Entire Site" the first time I searched and got no results. The links above are from searching the vulnerabilities.