Index: src/wp-includes/class-wp.php
===================================================================
--- src/wp-includes/class-wp.php	(revision 56184)
+++ src/wp-includes/class-wp.php	(working copy)
@@ -760,6 +760,13 @@
 		} else {
 			status_header( 200 );
 		}
+		
+		$post_id = $wp_query->post->ID;
+		$post = get_post($post_id);
+
+		if ( !empty( $post->post_password ) ) {
+			status_header( 403 );
+		}
 	}
 
 	/**