export.php (aka the export script) in phpMyAdmin 4.x before 4.0.0-rc3 overwrites global variables on the basis of the contents of the POST superglobal array, which allows remote authenticated users to inject values via a crafted request.
http://www.phpmyadmin.net/home_page/security/PMASA-2013-5.php
http://archives.neohapsis.com/archives/bugtraq/2013-04/0217.html