The mysql_uninstall_plugin function in sql/sql_plugin.cc in MySQL 5.1 before 5.1.46 does not check privileges before uninstalling a plugin, which allows remote attackers to uninstall arbitrary plugins via the UNINSTALL PLUGIN command.
http://bugs.mysql.com/bug.php?id=51770
http://dev.mysql.com/doc/refman/5.1/en/news-5-1-46.html
http://www.mandriva.com/security/advisories?name=MDVSA-2010:093