MySQL < 5.1.49 and < 5.0.92 - Authenticated Denial of Service via EXPLAIN with Crafted SELECT UNION ORDER BY
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.