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."
5.5.47-1ubuntu0.14.04.15.5.49-0ubuntu0.14.04.15.6.30-0ubuntu0.14.04.15.7.12-0ubuntu15.6.22-rel71.0-0ubuntu25.6.22-rel71.0-0ubuntu45.6.22-rel71.0-0ubuntu4.15.6.34-26.19-0ubuntu0.16.04.1Exploitability
AV:NAC:HPR:NUI:NScope
S:UImpact
C:NI:HA:NCVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N