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Links with URIs of schemes other than http/https are broken

On revision 5 of How to read Firefox "about:memory" correctly? I tried to set markdown links to about:memory (a special "URL" similar to about:config supported by Mozilla based browsers), ad it didn't work...

  • When I tried the naive thing (using the link button and pasting about:memory), the editor set the link to http://about:memory which obviously didn't work.
  • When I edited the "target" portion of the link syntax to be about:memory it was not rendered as a link.
  • Even trying <a href="about:memory">about:memory</a> does not seem to work in the live preview. I didn't submit that edit because there didn't seem to be a reason to further pollute the edit history.


Admittedly it is a rare use case, but should our markdown support a broad selection of "protocols"? If not, should pure html support it?

  • See here for a very similar post, which, other than pointing out that a supporting change is not likely to be implemented, also points out that such links won't necessarily work from an 'unsecure' page anyway (I'm not certain of the applicability to FireFox, though.) Commented Aug 23, 2011 at 22:36

1 Answer 1


If this was implemented I think it would need to use a whitelist. Lots of "protocols" are used to invoke third-party programs and could be abused.

For example, I don't want to click a "documentation" link and suddenly find myself downloading and helping to distribute malware because it was actually a magnet: link.

  • Good point. And and some point it just becomes more trouble than it is worth for a few use cases... Commented Aug 23, 2011 at 22:29
  • It didn't occur to me that cross-protocol redirects could entirely subvert this. badp pointed out that even TinyURL supports them; here's a magnet link to September's data dump: tinyurl.com/7yvfnsb
    – Jeremy
    Commented Jan 22, 2012 at 20:59

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