Index: wp-includes/class-wp.php
===================================================================
--- wp-includes/class-wp.php	(Revision 35604)
+++ wp-includes/class-wp.php	(Arbeitskopie)
@@ -437,6 +437,11 @@
 			}
 		}
 
+		if ( is_ssl() ) {
+			$headers['Content-Security-Policy'] = 'upgrade-insecure-requests';
+		}
+		
+		
 		/**
 		 * Filter the HTTP headers before they're sent to the browser.
 		 *