Index: class-http.php
===================================================================
--- class-http.php	(revision 25936)
+++ class-http.php	(working copy)
@@ -525,7 +525,14 @@
 		static $accessible_hosts;
 		static $wildcard_regex = false;
 		if ( null == $accessible_hosts ) {
-			$accessible_hosts = preg_split('|,\s*|', WP_ACCESSIBLE_HOSTS);
+			/**
+			 * Filter the list of accessible hosts.
+			 *
+			 * @since 3.8
+			 *
+			 * @param array List of accessible hosts
+			 */
+			$accessible_hosts = apply_filters( 'wp_accessible_hosts', preg_split( '|,\s*|', WP_ACCESSIBLE_HOSTS ) );
 
 			if ( false !== strpos(WP_ACCESSIBLE_HOSTS, '*') ) {
 				$wildcard_regex = array();