source: https://www.securityfocus.com/bid/9725/info

ezboard is prone to an HTML injection vulnerability. An attacker may exploit this issue by including hostile HTML and script code encapsulated in [font] tags of posts to the bulletin board. This code may be rendered in the web browser of a user who views these areas of the site. This would occur in the security context of the site hosting ezboard.

[font color=red;background:url(javascript:alert(document.cookie))]Big Exploit![/font]
[font face=Verdana;background:url(javascript:alert(document.cookie))]Big Exploit![/font]