Tasha Drew reports:

Researchers investigating the Rails parameter parsing vulnerability discovered 
that the same or similar vulnerable code had made its way into multiple other 
libraries. If your application uses these libraries to process untrusted data, 
it may still be vulnerable even if you have upgraded Rails. Check your Gemfile 
and Gemfile.lock for vulnerable versions of the following libraries, and if you
are using one, update it immediately.

You can update each of these by using "bundle update <gem name>". 

extlib

Vulnerable: <= 0.9.15

Fixed: 0.9.16

External references:
https://support.cloud.engineyard.com/entries/22915701-january-14-2013-security-vulnerabilities-httparty-extlib-crack-nori-update-these-gems-immediately

https://github.com/datamapper/extlib/compare/b4f98174ec35ac96f76a08d5624fad05d22879b5%E2%80%A64540e7102b803624cc2eade4bb8aaaa934fc31c5

https://rubygems.org/gems/extlib/