Index: wp-includes/link-template.php
===================================================================
--- wp-includes/link-template.php	(revision 17369)
+++ wp-includes/link-template.php	(working copy)
@@ -1526,7 +1526,7 @@
 
 	$result = apply_filters('get_pagenum_link', $result);
 
-	return $result;
+	return esc_url( $result );
 }
 
 /**