Configuring X-XSS-Protection¶

There are two configuration options

  • policy can be set to :
    • Disabled
    • FilterDisabled
    • FilterEnabled
  • blockMode adds mode=block in the header, defaults to false
Configuration Resulting header
policy=”Disabled” None
policy=”FilterDisabled” X-XSS-Protection: 0
policy=”FilterEnabled” blockMode=”true” X-XSS-Protection: 1; mode=block

In web.config:

<x-XSS-Protection policy="FilterEnabled" blockMode="true"/>
<x-XSS-Protection policy="FilterDisabled" />

NWebsec.Owin (ASP.NET 4): Register the middleware in the OWIN startup class:

using NWebsec.Owin;
public void Configuration(IAppBuilder app)
    app.UseXXssProtection(options => options.EnabledWithBlockMode());

Or as an MVC attribute, defaults to “FilterDisabled” blockMode=”true”:

[XXssProtection(Policy = XXssProtectionPolicy.Disabled)]

The header is omitted for redirects and static content.