Subject says it all. Malicious web sites have an open door, as the option to turn it off is buried in the preferences. Liferea can use the gnome browser mechanism, or several other browsers. I have not checked if the option is promoted to them, but then, if not, why have the option, at all?
Also reported upstream.
Please, don't restrict bugs without any reason. Anyway, this it certainly not a Gentoo issue.