I was pointing out the dangers of user-permitted HTML markup many years ago
when I talked about how I was including Barney the Dinosaur into guestbooks
on my home page.
I don't think there's a completely secure solution. tilly wrote a fairly
nice strongbox solution that permits very carefully a subset of HTML,
but it's more in the "only permitted things allowed" realm than the "look
for bad things and prevent them" realm. Given the risk, I'd say this is the right
-- Randal L. Schwartz, Perl hacker
Thanks to mdillon
for the link for tilly's node.