sql_select.cc in MySQL 5.0.x before 5.0.32 and 5.1.x before 5.1.14 allows remote authenticated users to cause a denial of service (crash) via an EXPLAIN SELECT FROM on the INFORMATION_SCHEMA table, as originally demonstrated using ORDER BY.
Improper Neutralization of Special Elements used in an SQL Command The product constructs all or part of an SQL command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended SQL command when it is sent to a downstream component. Without sufficient removal or quoting of SQL syntax in user-controllable inputs, the generated SQL query can cause those inputs to be interpreted as SQL instead of ordinary user data.