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://www.ubuntu.com/usn/USN-1397-1
http://www.securityfocus.com/bid/39543
http://www.mandriva.com/security/advisories?name=MDVSA-2010:093