Apache NiFi JMS Deserialization issue because of ActiveMQ client vulnerability. Malicious JMS content could cause denial of service. See ActiveMQ CVE-2015-5254 announcement for more information. The fix to upgrade the activemq-client library to 5.15.3 was applied on the Apache NiFi 1.6.0 release. Users running a prior 1.x release should upgrade to the appropriate release.

Apache ActiveMQ 5.x before 5.13.0 does not restrict the classes that can be serialized in the broker, which allows remote attackers to execute arbitrary code via a crafted serialized Java Message Service (JMS) ObjectMessage object.