A week or so ago I received an e-mail from a nice new zealander, Simon Greenhill, alerting me to a cross-site scripting vulnerability in the comments portion of my blog. The vulnerability will actually probably be of concern to anybody using the comments module from Django - I haven't dug far enough into it as yet to confirm exactly what's at risk.
If you read on, you can see the contents of the e-mail he sent through to me. Basically, the 'name' field from the comments needs to be escaped at the time when the comment preview is displayed. I patched my code some time ago, but now I've got the chance I'm making it public to help everybody else out.
His e-mail said this:
So, if you've copied my comments code off this site, it's probably worth making that change for now, until at least Django automatically handles this (to be honest, I thought django.contrib.comments would automatically do this - but I'm sure there's a reason against it) or I can find a 'better' way around it.