The serialization implementation in JBoss Drools in Red Hat JBoss Enterprise Application Platform (aka JBoss EAP or JBEAP) 4.3 before 4.3.0.CP09 and JBoss Enterprise SOA Platform 4.2 and 4.3 supports the embedding of class files, which allows remote attackers to execute arbitrary code via a crafted static initializer.
https://issues.jboss.org/browse/SOA-2319
https://bugzilla.redhat.com/show_bug.cgi?id=633859
http://www.redhat.com/support/errata/RHSA-2010-0940.html
http://www.redhat.com/support/errata/RHSA-2010-0939.html
http://www.redhat.com/support/errata/RHSA-2010-0938.html