The AMQP type decoder in Apache Qpid 0.20 and earlier allows remote attackers to cause a denial of service (memory consumption and server crash) via a large number of zero width elements in the client-properties map in a connection.start-ok message.
rhn.redhat.com/errata/RHSA-2013-0561.html
rhn.redhat.com/errata/RHSA-2013-0562.html
secunia.com/advisories/52516
svn.apache.org/viewvc?view=revision&revision=1453031
bugzilla.redhat.com/show_bug.cgi?id=861234
issues.apache.org/jira/browse/QPID-4629
issues.apache.org/jira/issues/?jql=fixVersion%20%3D%20%220.21%22%20AND%20project%20%3D%20QPID