Cross-site scripting (XSS) vulnerability in the choose_primary_blog function in wp-includes/wpmu-functions.php in WordPress MU (WPMU) before 2.7 allows remote attackers to inject arbitrary web script or HTML via the HTTP Host header.
https://www.exploit-db.com/exploits/8196
https://exchange.xforce.ibmcloud.com/vulnerabilities/49184
http://www.securitytracker.com/id?1021838
http://www.securityfocus.com/bid/34075
http://www.securityfocus.com/archive/1/501667/100/0/threaded