Super Search brings some links to similar discussions :

• Stay aware of security
• Security
• Secrets & Lies & Perl

Of course perlsec is also a must read...

UPDATE :
Of course, the main Perl vulnerability, is the bad programming practices...
This is often NOT related to Perl.
Some scripts are "known" to be poorly coded
(see all the discussions about Matt's script archive or better the davorg's project to rewrite them properly...)

"Only Bad Coders Code Badly In Perl" (OBC2BIP)