The ssl_verify_server_cert function in sql-common/client.c in MariaDB before 5.5.47, 10.0.x before 10.0.23, and 10.1.x before 10.1.10; Oracle MySQL 5.5.48 and earlier, 5.6.29 and earlier, and 5.7.11 and earlier; and Percona Server do not properly verify that the server hostname matches a domain name in the subject's Common Name (CN) or subjectAltName field of the X.509 certificate, which allows man-in-the-middle attackers to spoof SSL servers via a "/CN=" string in a field in a certificate, as demonstrated by "/OU=/CN=bar.com/CN=foo.com."
https://mariadb.com/kb/en/mdb-10023-rn/
https://mariadb.com/kb/en/mariadb/mariadb-5547-release-notes/
https://mariadb.com/kb/en/mariadb/mariadb-10110-release-notes/
https://mariadb.atlassian.net/browse/MDEV-9212
https://access.redhat.com/errata/RHSA-2016:1132
http://www.ubuntu.com/usn/USN-2954-1
http://www.ubuntu.com/usn/USN-2953-1
http://www.securitytracker.com/id/1035606
http://www.securityfocus.com/bid/81810
http://www.oracle.com/technetwork/topics/security/linuxbulletinapr2016-2952096.html
http://www.oracle.com/technetwork/security-advisory/cpuapr2016v3-2985753.html
http://www.openwall.com/lists/oss-security/2016/01/26/3
http://www.debian.org/security/2016/dsa-3557
http://www.debian.org/security/2016/dsa-3453
http://rhn.redhat.com/errata/RHSA-2016-1481.html
http://rhn.redhat.com/errata/RHSA-2016-1480.html
http://rhn.redhat.com/errata/RHSA-2016-0705.html
http://rhn.redhat.com/errata/RHSA-2016-0534.html
http://lists.opensuse.org/opensuse-security-announce/2016-06/msg00053.html
http://lists.opensuse.org/opensuse-security-announce/2016-06/msg00051.html
http://lists.opensuse.org/opensuse-security-announce/2016-06/msg00034.html
http://lists.opensuse.org/opensuse-security-announce/2016-06/msg00033.html
http://lists.opensuse.org/opensuse-security-announce/2016-05/msg00053.html
http://lists.opensuse.org/opensuse-security-announce/2016-05/msg00035.html