Cross-site scripting (XSS) vulnerability in cookieauth.dll in the HTML forms authentication component in Microsoft Forefront Threat Management Gateway, Medium Business Edition (TMG MBE); and Internet Security and Acceleration (ISA) Server 2006, 2006 Supportability Update, and 2006 SP1; allows remote attackers to inject arbitrary web script or HTML via "authentication input" to this component, aka "Cross-Site Scripting Vulnerability."