diff --git a/core/includes/form.inc b/core/includes/form.inc
index 5aafe81..9948076 100644
--- a/core/includes/form.inc
+++ b/core/includes/form.inc
@@ -357,7 +357,7 @@ function template_preprocess_details(&$variables) {
     $variables['summary_attributes']['aria-expanded'] = !empty($element['#attributes']['open']);
     $variables['summary_attributes']['aria-pressed'] = $variables['summary_attributes']['aria-expanded'];
   }
-  $variables['title'] = (!empty($element['#title'])) ? $element['#title'] : '';
+  $variables['title'] = (!empty($element['#title'])) ? Xss::filterAdmin($element['#title']) : '';
   $variables['description'] = (!empty($element['#description'])) ? $element['#description'] : '';
   $variables['children'] = (isset($element['#children'])) ? $element['#children'] : '';
   $variables['value'] = (isset($element['#value'])) ? $element['#value'] : '';