source: https://www.securityfocus.com/bid/3906/info

PHPNuke is a website creation/maintenance tool. It is can be back-ended by a number of database products such as MySQL, PostgreSQL, mSQL, Interbase, Sybase, etc.

The sql_layer.php script contains a debugging feature that may be used by attackers to disclose sensitive information about all SQL queries made by PHPNuke. Access to the debugging feature is not restricted to administrators.

This may be used by a remote attacker to disclose sensitive information about the database which may contribute to further attacks against the website running PHPNuke and the database.

It is not known whether PostNuke is also affected by this issue. 

The following URLs may be used to access the debugging features:

http://www.vulnerable-site.com/index.php?sql_debug=1

or

http://www.vulnerable-site.com/modules.php?name=Members_List&&sql_debug=1