Invision Power Board (aka IPB or IP.Board) 2.x through 3.0.4, when Internet Explorer 5 is used, allows XSS via a .txt attachment.
https://www.securityfocus.com/bid/37263/info
https://www.exploit-db.com/exploits/33394
https://packetstormsecurity.com/files/83624/Invision-Power-Board-3.0.4-Cross-Site-Scripting.html
https://euvd.enisa.europa.eu/vulnerability/EUVD-2009-5113
http://community.invisionpower.com/topic/300051-invision-power-board-305-released/