The bbcode plugin in TinyMCE 3.5.8 does not properly enforce the TinyMCE security policy for the (1) encoding directive and (2) valid_elements attribute, which allows attackers to conduct cross-site scripting (XSS) attacks via application-specific vectors, as demonstrated using a textarea element.
https://exchange.xforce.ibmcloud.com/vulnerabilities/82744
https://euvd.enisa.europa.eu/vulnerability/EUVD-2012-4174
http://www.securityfocus.com/bid/58424
http://seclists.org/fulldisclosure/2013/Mar/114
http://packetstormsecurity.com/files/120750/TinyMCE-3.5.8-Cross-Site-Scripting.html