All MariaDB and MySQL versions up to 5.1.61, 5.2.11, 5.3.5, 5.5.22 are vulnerable.
MariaDB versions from 5.1.62, 5.2.12, 5.3.6, 5.5.23 are not.
MySQL versions from 5.1.63, 5.5.24, 5.6.6 are not.
Which means, if one knows a user name to connect (and “root” almost always exists), she can connect using any password by repeating connection attempts. ~300 attempts takes only a fraction of second, so basically account password protection is as good as nonexistent. Any client will do, there’s no need for a special libmysqlclient library.