The org.apache.catalina.connector.Response.encodeURL method in Red Hat JBoss Web 7.1.x and earlier, when the tracking mode is set to COOKIE, sends the jsessionid in the URL of the first response of a session, which allows remote attackers to obtain the session id (1) via a man-in-the-middle attack or (2) by reading a log.
https://issues.jboss.org/browse/JBWEB-249
http://rhn.redhat.com/errata/RHSA-2013-1437.html
http://rhn.redhat.com/errata/RHSA-2013-0839.html
http://rhn.redhat.com/errata/RHSA-2013-0834.html
http://rhn.redhat.com/errata/RHSA-2013-0833.html
http://ocpsoft.org/support/topic/session-id-is-appended-as-url-path-parameter-in-very-first-request/