Cross-site scripting (XSS) vulnerability in Phorum before 3.4.3 allows remote attackers to inject arbitrary web script and HTML tags via a message with a "<<" before a tag name in the (1) subject, (2) author's name, or (3) author's e-mail.
https://exchange.xforce.ibmcloud.com/vulnerabilities/11974
http://www.securityfocus.com/bid/7545