The optional ActiveMQ LDAP login module can be configured to use anonymous access to the LDAP server. In this case, for Apache ActiveMQ Artemis prior to version 2.16.0 and Apache ActiveMQ prior to versions 5.16.1 and 5.15.14, the anonymous context is used to verify a valid users password in error, resulting in no check on the password.
It was found that when Artemis and HornetQ before 2.4.0 are configured with UDP discovery and JGroups discovery a huge byte array is created when receiving an unexpected multicast message. This may result in a heap memory exhaustion, full GC, or OutOfMemoryError.
The getObject method of the javax.jms.ObjectMessage class in the (1) JMS Core client, (2) Artemis broker, and (3) Artemis REST component in Apache ActiveMQ Artemis before 1.4.0 might allow remote authenticated users with permission to send messages to the Artemis broker to deserialize arbitrary objects and execute arbitrary code by leveraging gadget classes being present on the Artemis classpath.