While I understand (and agree with) the security implications in general, what are the added implications of making the variable that already exists accept multiple paths instead of just a single path.

H::T currently looks in the single path pointed to by HTML_TEMPLATE_ROOT. I am having a hard time seeing how multiple paths (ala PATH, MANPATH, PERL5LIB, etc) in an already existing single-path variable is more of a security risk. At worst I can see a performance hit.

I think that I may have tried to generalize my original post too much, when I should have focused it explicitly on just HTML_TEMPLATE_ROOT.