RedCloth contains unfixed XSS vulnerability for 9 years

[Kousuke Ebihara <kousuke () co3k org>]

I disclosed the following advisory about a XSS vulnerability of
RedCloth (Textile library for Ruby).
http://co3k.org/blog/redcloth-unfixed-xss-en

You shouldn't use RedCloth to parse user inputted contents and output
the parsed string (except that you allow your
user to write arbitrary JavaScript code on your site) because it
contains unfixed XSS vulnerability for 9 years,
and it be also disclosed for 2 years.

Unfortunately, we may not expect fix the vulnerability by the current
developer because he announced that "unable to
keep fixing bugs or work on the next major release".

If you want to continue to use RedCloth for such contents, you should
patch for the problem yourself, consider
contributing to RedCloth, or otherwise.

PoC
===

```
require 'redcloth'

print RedCloth.new('["clickme":javascript:alert(%27XSS%27)]',
[:filter_html, :filter_styles, :filter_classes, :filter_ids]).to_html

# Result:
# <p><a href="javascript:alert(%27XSS%27)">clickme</a></p>
```

Timeline
========

* Feb. 24, 2012 : I reported the problem to a developer (by sending e-mail)
* Feb. 29, 2012 : A developer discloses the issue in this ticket:
http://jgarber.lighthouseapp.com/projects/13054-redcloth/tickets/243-xss
* ...
* Sep. 24, 2014 : Announced "RedCloth needs new maintainers" to take
over RedCloth by a developer:
https://github.com/jgarber/redcloth/commit/b24f03db023d1653d60dd33b28e09317cd77c6a0

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