Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
The default configuration of ASP.NET in Mono before 2.6.4 has a value of FALSE for the EnableViewStateMac property, which allows remote attackers to conduct cross-site scripting (XSS) attacks, as demonstrated by the __VIEWSTATE parameter to 2.0/menu/menu1.aspx in the XSP sample project.