In the Kunena extension 5.0.2 through 5.0.4 for Joomla! the forum message subject (aka topic subject) accepts JavaScript leading to XSS. Six files are affected: crypsis/layouts/message/item/default.php crypsis/layouts/message/item/top/default.php crypsis/layouts/message/item/bottom/default.php crypsisb3/layouts/message/item/default.php crypsisb3/layouts/message/item/top/default.php and crypsisb3/layouts/message/item/bottom/default.php. This is fixed in 5.0.5.