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A NULL pointer derefence flaw was found in the way MySQL server processed certain SQL queries requesting EXPLAIN for a SELECT from a derived table in prepared-statement mode. A remote attacker, valid SQL user could use this flaw to cause denial of service (mysqld daemon crash). References: [1] http://dev.mysql.com/doc/refman/5.1/en/news-5-1-52.html [2] http://bugs.mysql.com/bug.php?id=54488 Note: On Red Hat Enterprise Linux systems exploitation of this issue would lead only to temporary denial of service, since mysqld daemon gets automatically restarted upon encountering a crash.
Public PoC from [2]: ==================== drop table if exists `t1`; create table `t1`(`a` int)engine=myisam; insert into `t1` values (1),(1); prepare `stmt` from 'explain select 1 from `t1` where(select(select 1 from `t1` group by `a`))'; execute `stmt` ;
This issue did NOT affect the version of the mysql package, as shipped with Red Hat Enterprise Linux 4. This issue affects the version of the mysql package, as shipped with Red Hat Enterprise Linux 5. This issue did NOT affect the version of the mysql package, as shipped with Red Hat Enterprise Linux 6. -- This issue did NOT affect the versions of the mysql package, as shipped with Fedora release of 14 and 15.
(In reply to comment #2) > This issue affects the version of the mysql package, as shipped with > Red Hat Enterprise Linux 5. The mysql package in Red Hat Enterprise Linux 5 has been upgraded to version 5.0.95 via RHSA-2012:0127 security advisory: https://rhn.redhat.com/errata/RHSA-2012-0127.html, and therefore this issue has been addressed in Red Hat Enterprise Linux 5 too.