hfy-html-quote-regex

hfy-html-quote-regex is a variable defined in `htmlfontify.el'.
Its value is

"\\([<\"&>]\\)"

Documentation:
Regex to match (with a single back-reference per match) strings in HTML
which should be quoted with `hfy-html-quote' (and `hfy-html-quote-map')
to make them safe.

You can customize this variable.