Cross-site scripting (XSS) vulnerability in FlatNuke 2.5.3 allows remote attackers to inject arbitrary web script or HTML via the border or back parameters to (1) help.php or (2) footer.php.
FlatNuke 2.5.3 allows remote attackers to obtain sensitive information via invalid parameters to certain scripts, which leaks the web document root in an error message.
Direct code injection vulnerability in FlatNuke 2.5.3 allows remote attackers to execute arbitrary PHP code by placing the code into the Referer header of an HTTP request, which causes the code to be injected into referer.php, which can then be accessed by the attacker.