The Qpid Broker for Java can be configured to use different so
called AuthenticationProviders to handle user authentication.
Among the choices are the SCRAM-SHA-1 and SCRAM-SHA-256
AuthenticationProvider types.
It was discovered that these AuthenticationProviders prematurely
terminate the SCRAM SASL negotiation if the provided user name
does not exist thus allowing remote attacker to determine the
existence of user accounts.
The Vulnerability does not apply to AuthenticationProviders other
than SCRAM-SHA-1 and SCRAM-SHA-256.
References:
http://seclists.org/oss-sec/2016/q4/772
Upstream bug:
https://issues.apache.org/jira/browse/QPID-7599