The executable comment feature in MySQL 5.0.x before 5.0.93 and 5.1.x before 5.1.50, when running in certain slave configurations in which the slave is running a newer version than the master, allows remote attackers to execute arbitrary SQL commands via custom comments.
http://secunia.com/advisories/49179
http://seclists.org/oss-sec/2011/q4/101
http://lists.opensuse.org/opensuse-security-announce/2012-08/msg00007.html