PHP-Nuke 7.3, and other products that use the PHP-Nuke codebase such as the Nuke Cops betaNC PHP-Nuke Bundle, OSCNukeLite 3.1, and OSC2Nuke 7x do not properly use the eregi() PHP function with $_SERVER['PHP_SELF'] to identify the calling script, which allows remote attackers to directly access scripts, obtain path information via a PHP error message, and possibly gain access, as demonstrated using an HTTP request that contains the "admin.php" string.

Cross-site scripting (XSS) vulnerability in the Your_Account module for PHP-Nuke 5.0 through 6.0 allows remote attackers to inject arbitrary web script or HTML via the user_avatar parameter.

sql_layer.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 sql_debug parameter to (1) index.php and (2) modules.php.

index.php for PHP-Nuke 5.4 and earlier allows remote attackers to determine the physical pathname of the web server when the file parameter is set to index.php, which triggers an error message that leaks the pathname.

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.

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.

PHP-Nuke 5.1 stores user and administrator passwords in a base-64 encoded cookie, which could allow remote attackers to gain privileges by stealing or sniffing the cookie and decoding it.