sqllayer.php in PHP-Nuke 5.4 and earlier does not restrict access to debugging features, which allows remote attackers to gain SQL query information by setting the sqldebug parameter to (1) index.php and (2) modules.php.

Cross-site scripting (XSS) vulnerability in PHP-Nuke 5.3.1 and earlier allows remote attackers to inject arbitrary web script or HTML via the (1) uname parameter in user.php, (2) ttitle, letter and file parameters in modules.php, (3) subject, story and storyext parameters in submit.php, (4) upload parameter in admin.php and (5) fname parameter in friend.php.

index.php in Francisco Burzi PHP-Nuke 5.3.1 and earlier, and possibly other versions before 5.5, allows remote attackers to execute arbitrary PHP code by specifying a URL to the malicious code in the file parameter.

SQL injection vulnerability in PHP-Nuke 6.9 and earlier, and possibly 7.x, allows remote attackers to inject arbitrary SQL code and gain sensitive information via (1) the category variable in the Search module or (2) the admin variable in the WebLinks module.

Cross-site request forgery (CSRF) vulnerability in admin.php in Francisco Burzi PHP-Nuke allows remote attackers to add administrative accounts via an AddAuthor action with modified addname and addradminsuper parameters.