CRLF injection vulnerability in index.php in ExpressionEngine 1.2.1 and earlier allows remote attackers to inject arbitrary HTTP headers and conduct HTTP response splitting attacks via the URL parameter.
http://www.securityfocus.com/bid/27128
http://www.securityfocus.com/archive/1/485786/100/0/threaded
http://websecurity.com.ua/1454/
http://securityvulns.ru/Sdocument472.html
http://securityreason.com/securityalert/3539
http://lists.grok.org.uk/pipermail/full-disclosure/2008-January/059439.html