portal/server.pt in the Plumtree portal in BEA AquaLogic Interaction 5.0.2 through 5.0.4 and 6.0.1.218452 allows wildcards in advanced searches for usernames, which allows remote attackers to enumerate valid usernames via the in_tx_fulltext parameter.
http://www.vupen.com/english/advisories/2007/4040
http://www.securitytracker.com/id?1019004
http://www.securityfocus.com/archive/1/484469/100/0/threaded