If, after successful installation of MantisBT through 2.5.2 on MySQL/MariaDB, the administrator does not remove the 'admin' directory (as recommended in the "Post-installation and upgrade tasks" section of the MantisBT Admin Guide), and the MySQL client has a local_infile setting enabled (in php.ini mysqli.allow_local_infile, or the MySQL client config file, depending on the PHP setup), an attacker may take advantage of MySQL's "connect file read" feature to remotely access files on the MantisBT server.

Oracle MySQL 5.1 before 5.1.49 and 5.0 before 5.0.92 allows remote authenticated users to cause a denial of service (mysqld daemon crash) by using EXPLAIN with crafted "SELECT ... UNION ... ORDER BY (SELECT ... WHERE ...)" statements, which triggers a NULL pointer dereference in the Item_singlerow_subselect::store function.

Oracle MySQL 5.1 before 5.1.49 and 5.0 before 5.0.92 allows remote authenticated users to cause a denial of service (mysqld daemon crash) via a join query that uses a table with a unique SET column.

The mysql-ocaml bindings 1.0.4 for MySQL do not properly support the mysql_real_escape_string function, which might allow remote attackers to leverage escaping issues involving multibyte character encodings.