Oracle MySQL and MariaDB 5.5.x before 5.5.29, 5.3.x before 5.3.12, and 5.2.x before 5.2.14 does not modify the salt during multiple executions of the change_user command within the same connection which makes it easier for remote authenticated users to conduct brute force password guessing attacks.
seclists.org/fulldisclosure/2012/Dec/58
seclists.org/fulldisclosure/2012/Dec/83
seclists.org/oss-sec/2012/q4/424
secunia.com/advisories/53372
security.gentoo.org/glsa/glsa-201308-06.xml
www.mandriva.com/security/advisories?name=MDVSA-2013:102
bugzilla.redhat.com/show_bug.cgi?id=883719
mariadb.atlassian.net/browse/MDEV-3915