includes/bootstrap.inc in Drupal 5.x before 5.12 and 6.x before 6.6, when the server is configured for "IP-based virtual hosts," allows remote attackers to include and execute arbitrary files via the HTTP Host header.
https://www.redhat.com/archives/fedora-package-announce/2008-October/msg00826.html
https://www.redhat.com/archives/fedora-package-announce/2008-October/msg00783.html
https://exchange.xforce.ibmcloud.com/vulnerabilities/46049
http://www.vupen.com/english/advisories/2008/2913
http://www.securityfocus.com/bid/31900
http://secunia.com/advisories/32441