phpMyAdmin is a tool written in PHP intended to handle the administration of MySQL over the web.
Stefan Esser discovered that by calling certain PHP files directly, it was possible to workaround the grab_globals.lib.php security model and overwrite the $cfg configuration array. Systems running PHP in safe mode are not affected. Futhermore, Tobias Klein reported several cross-site-scripting issues resulting from insufficient user input sanitizing.
A local attacker may exploit this vulnerability by sending malicious requests, causing the execution of arbitrary code with the rights of the user running the web server. Furthermore, the cross-site scripting issues give a remote attacker the ability to inject and execute malicious script code or to steal cookie-based authentication credentials, potentially compromising the victim's browser.
There is no known workaround for all those issues at this time.
All phpMyAdmin users should upgrade to the latest version:
# emerge --sync
# emerge --ask --oneshot --verbose ">=dev-db/phpmyadmin-2.6.4_p3"