Gets or sets a value that indicates whether request validation is enabled for this request.
Namespace:  System.Web.Mvc
Assembly:  System.Web.Mvc (in System.Web.Mvc.dll)
Syntax
'Declaration
Public Property ValidateRequest As Boolean
    Get
    Set
public bool ValidateRequest { get; set; }
public:
property bool ValidateRequest {
    bool get ();
    void set (bool value);
}
Property Value
Type: System.Boolean
true if request validation is enabled for this request; otherwise, false. The default is true.
Remarks
In ASP.NET 4, setting the ValidateRequest to false has no effect because validation takes place before the MVC pipeline receives the request. Therefore, in ASP.NET 4 you must set the RequestValidationMode property to a version lower than 4.0. You can configure the validation mode in the Web.config file by using the RequestValidationMode attribute of the httpRuntime element, as shown in the following example:
<system.web>
   <httpRuntime  requestValidationMode="2.0" />
</system.web>
For more information see httpRuntime Element (ASP.NET Settings Schema).