diff --git a/core/lib/Drupal/Component/Utility/Xss.php b/core/lib/Drupal/Component/Utility/Xss.php
index 071ebd9..a68ca2b 100644
--- a/core/lib/Drupal/Component/Utility/Xss.php
+++ b/core/lib/Drupal/Component/Utility/Xss.php
@@ -237,7 +237,6 @@ protected static function attributes($attributes) {
             $skip_protocol_filtering = substr($attribute_name, 0, 5) === 'data-' || in_array($attribute_name, array(
               'title',
               'alt',
-              'rel',
             ));
 
             $working = $mode = 1;
diff --git a/core/modules/rdf/rdf.module b/core/modules/rdf/rdf.module
index e6c303a..b4d3313 100644
--- a/core/modules/rdf/rdf.module
+++ b/core/modules/rdf/rdf.module
@@ -445,8 +445,11 @@ function rdf_preprocess_comment(&$variables) {
     // comment.html.twig.
     foreach (['author', 'submitted'] as $variable) {
       $variables[$variable] = [
-        '#type' => 'markup',
-        '#markup' => '<span ' . new Attribute($author_attributes) . '>' . $variables[$variable] . '</span>',
+        '#type' => 'inline_template',
+        '#template' => '<span' . new Attribute($author_attributes) . '>{{ var }}</span>',
+        '#context' => array(
+          'var' => $variables[$variable],
+        ),
       ];
     }
   }