feed: URLs with an innerURI inherit security context of page — Mozilla

Security researchers Mario Gomes and Soroush Dalili reported that since Mozilla allows the pseudo-protocol feed: to prefix any valid URL, it is possible to construct feed:javascript: URLs that will execute scripts in some contexts. On some sites it may be possible to use this to evade output filtering that would otherwise strip javascript: URLs and thus contribute to cross-site scripting (XSS) problems on these sites.