The sanitize helper in lib/action_controller/vendor/html-scanner/html/sanitizer.rb in the Action Pack component in Ruby on Rails before 2.3.18, 3.0.x and 3.1.x before 3.1.12, and 3.2.x before 3.2.13 does not properly handle encoded : (colon) characters in URLs, which makes it easier for remote attackers to conduct cross-site scripting (XSS) attacks via a crafted scheme name, as demonstrated by including a : sequence.

References

• https://nvd.nist.gov/vuln/detail/CVE-2013-1857
• https://groups.google.com/group/rubyonrails-security/msg/78b9817a5943f6d6?dmode=source&output=gplain
• http://lists.opensuse.org/opensuse-updates/2013-04/msg00072.html
• http://lists.opensuse.org/opensuse-updates/2013-04/msg00073.html
• http://lists.opensuse.org/opensuse-updates/2014-01/msg00013.html
• http://rhn.redhat.com/errata/RHSA-2013-0698.html
• http://rhn.redhat.com/errata/RHSA-2014-1863.html
• http://support.apple.com/kb/HT5784
• http://weblog.rubyonrails.org/2013/3/18/SEC-ANN-Rails-3-2-13-3-1-12-and-2-3-18-have-been-released/
• https://web.archive.org/web/20130609174600/http://lists.apple.com/archives/security-announce/2013/Jun/msg00000.html
• https://web.archive.org/web/20131109010518/http://lists.apple.com/archives/security-announce/2013/Oct/msg00006.html