1. Go to chat

  2. Write "like http://xkcd.com"

  3. Wait a few moments for the submission to go through

  4. Resulting text is:

    Random semicolon activity

I tried a few variations and, as long as the URL is within a quoted passage, and some non-link text is prior within the quote, the semicolon appears.

More proof that this is a strange bug (as the two blocks in the below image ought to be identical):

(Thanks to the Robot for caring more than any human would.)

  • Also please note that my immediately subsequent comment in the original discussion was "no offence". Mar 30, 2015 at 0:37
  • I have a feeling this could be exploited in an XSS attack. Get the SE team now.
    – bwDraco
    Mar 30, 2015 at 0:44
  • awooga awooga.. Mar 30, 2015 at 0:44
  • Just contacted the team on this. We'll see what they say.
    – bwDraco
    Mar 30, 2015 at 1:16
  • 1
    @DragonLordtheFiery: I don't get it. Was this post not sufficient notification of the bug? Mar 30, 2015 at 1:18
  • 1
    Good grief, four years old and still not fixed! Mar 30, 2015 at 15:22

1 Answer 1


This is definitely an SO-Markdown bug of some sort, since the source is like this:

<div class="content">
    like when people go &quot;omg this is so funny <a href="http://xkcd.com&quot" rel="nofollow">xkcd.com&quot</a>; cos they&#39;re too stupid to realise that their link has a shelf life of, at most, three days                      

It's like the " has been HTML-encoded before linkification occurs.... then linkification goes up to the entity's ;, leaving &quot orphaned (and browsers tend to accept &quot rather than &quot; because Internet Explorer -5 set a precedent back in the late 1850s).

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