1 files changed, 7 insertions, 1 deletions
diff --git a/railties/lib/rails/application/default_middleware_stack.rb b/railties/lib/rails/application/default_middleware_stack.rb
index 8fe48feefb..0e79ba7da0 100644
--- a/railties/lib/rails/application/default_middleware_stack.rb
+++ b/railties/lib/rails/application/default_middleware_stack.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Rails
   class Application
     class DefaultMiddlewareStack
@@ -10,7 +12,7 @@ module Rails
       end
 
       def build_stack
-        ActionDispatch::MiddlewareStack.new.tap do |middleware|
+        ActionDispatch::MiddlewareStack.new do |middleware|
           if config.force_ssl
             middleware.use ::ActionDispatch::SSL, config.ssl_options
           end
@@ -61,6 +63,10 @@ module Rails
             middleware.use ::ActionDispatch::Flash
           end
 
+          unless config.api_only
+            middleware.use ::ActionDispatch::ContentSecurityPolicy::Middleware
+          end
+
           middleware.use ::Rack::Head
           middleware.use ::Rack::ConditionalGet
           middleware.use ::Rack::ETag, "no-cache"