TLS hostname verification when using the Apache ActiveMQ Client before 5.15.6 was missing which could make the client vulnerable to a MITM attack between a Java application using the ActiveMQ client and the ActiveMQ server. This is now enabled by default.
https://www.oracle.com/technetwork/security-advisory/cpujul2019-5072835.html
https://www.oracle.com/technetwork/security-advisory/cpujan2019-5072801.html
https://www.oracle.com/technetwork/security-advisory/cpuapr2019-5072813.html
https://www.oracle.com/security-alerts/cpujan2021.html
https://www.oracle.com/security-alerts/cpuapr2020.html
https://lists.debian.org/debian-lts-announce/2021/03/msg00005.html
https://access.redhat.com/errata/RHSA-2019:3892
http://www.securitytracker.com/id/1041618
http://www.securityfocus.com/bid/105335
http://activemq.apache.org/security-advisories.data/CVE-2018-11775-announcement.txt