Possible XSS vulnerability in rails-html-sanitizer

Metadata

medium
4.3
rails-html-sanitizer
CVE-2015-7580
groups.google.com
2016-01-25
2018-01-09 03:03
CVE-2015-7580 ruby-rails-html-sanitizer
CVE-2015-7580
2017-06-16 19:16
2017-04-01 19:10
2017-01-05 20:15

Description

There is a possible XSS vulnerability in the white list sanitizer in the
rails-html-sanitizer gem. This vulnerability has been assigned the CVE
identifier CVE-2015-7580.

Versions Affected: All.
Not affected: None.
Fixed Versions: v1.0.3

Impact
------
Carefully crafted strings can cause user input to bypass the sanitization in
the white list sanitizer which will can lead to an XSS attack.

Vulnerable code will look something like this:

<%= sanitize user_input, tags: %w(em) %>

All users running an affected release should either upgrade or use one of the
workarounds immediately.

Releases
--------
The FIXED releases are available at the normal locations.

Workarounds
-----------
Putting the following monkey patch in an initializer can help to mitigate the
issue:

```
class Rails::Html::PermitScrubber
alias :old_scrub :scrub
alias :old_skip_node? :skip_node?

def scrub(node)
if node.cdata?
text = node.document.create_text_node node.text
node.replace text
return CONTINUE
end
old_scrub node
end

def skip_node?(node); node.text?; end
end
```

Patches
-------
To aid users who aren't able to upgrade immediately we have provided patches for
the two supported release series. They are in git-am format and consist of a
single changeset.

* 1-0-whitelist_sanitizer_xss.patch - Patch for 1.0 series

Credits
-------
Thanks to Arnaud Germis, Nate Clark, and John Colvin for reporting this issue.

Am I vulnerable?

The constraints below list the versions that this vulnerability is patched in, and versions that are unaffected. If a patch is ready but unrealeased, then it is pending.

Or, you can just let us figure it out for you! Appcanary continously monitor your installed packages, and tell you if any of them are vulnerable.

Sign up for monitoring

Affected package information

Package Patched in Unaffected in
rails-html-sanitizer >= 1.0.3 None