MySQL is a multi-user, multi-threaded SQL database server. It consists of the MySQL server daemon and many client programs and libraries. A stack-based buffer overflow flaw was found in the user permission checking code in MySQL. An authenticated database user could use this flaw to crash the mysqld daemon or, potentially, execute arbitrary code with the privileges of the user running the mysqld daemon. A flaw was found in the way MySQL calculated the key length when creating a sort order index for certain queries. An authenticated database user could use this flaw to crash the mysqld daemon. This update also adds a patch for a potential flaw in the MySQL password checking function, which could allow an attacker to log into any MySQL account without knowing the correct password. This problem only affected MySQL packages that use a certain compiler and C library optimization. It did not affect the mysql packages in Red Hat Enterprise Linux 5. The patch is being added as a preventive measure to ensure this problem cannot get exposed in future revisions of the mysql packages. All MySQL users should upgrade to these updated packages, which correct these issues. After installing this update, the MySQL server daemon will be restarted automatically.