Ticket #44210: 44210.diff

src/wp-includes/http.php

@@ -596 +596 @@
                 return $url;
         }
 
+        /**
+         * Filter to allow for valid URLs from local servers.
+         *
+         * @since 4.9.x
+         *
+         * @return bool
+         */
+        if ( apply_filters( 'http_request_host_is_local', false ) ) {
+                return $url;
+        }
+
         return false;
 }