DeluxeBB 1.07 and earlier allows remote attackers to overwrite the (1) _GET, (2) _POST, (3) _ENV, and (4) _SERVER variables via the _COOKIE (aka COOKIE) variable, which can overwrite the other variables during an extract function call, probably leading to multiple security vulnerabilities, aka "pollution of the global namespace."
http://www.securityfocus.com/bid/19052
http://www.securityfocus.com/archive/1/440435/100/0/threaded
http://securityreason.com/securityalert/1254
http://lists.grok.org.uk/pipermail/full-disclosure/2006-July/047989.html