diff --git a/core/modules/system/system.admin.inc b/core/modules/system/system.admin.inc
index a45a0e3..766d3ee 100644
--- a/core/modules/system/system.admin.inc
+++ b/core/modules/system/system.admin.inc
@@ -893,7 +893,7 @@ function system_modules($form, $form_state = array()) {
   foreach (element_children($form['modules']) as $package) {
     $form['modules'][$package] += array(
       '#type' => 'fieldset',
-      '#title' => t($package),
+      '#title' => check_plain(t($package)),
       '#collapsible' => TRUE,
       '#theme' => 'system_modules_fieldset',
       '#header' => array(
@@ -958,13 +958,13 @@ function _system_modules_build_row($info, $extra) {
   );
   // Set the basic properties.
   $form['name'] = array(
-    '#markup' => $info['name'],
+    '#markup' => check_plain($info['name']),
   );
   $form['description'] = array(
-    '#markup' => t($info['description']),
+    '#markup' => filter_xss_admin(t($info['description'])),
   );
   $form['version'] = array(
-    '#markup' => $info['version'],
+    '#markup' => check_plain($info['version']),
   );
   $form['#requires'] = $extra['requires'];
   $form['#required_by'] = $extra['required_by'];
@@ -2721,13 +2721,13 @@ function theme_system_themes_page($variables) {
       $screenshot = $theme->screenshot ? theme('image', $theme->screenshot) : '<div class="no-screenshot">' . t('no screenshot') . '</div>';
 
       // Localize the theme description.
-      $description = t($theme->info['description']);
+      $description = filter_xss_admin(t($theme->info['description']));
 
       // Style theme info
       $notes = count($theme->notes) ? ' (' . join(', ', $theme->notes) . ')' : '';
       $theme->classes[] = 'theme-selector';
       $theme->classes[] = 'clearfix';
-      $output .= '<div class="'. join(' ', $theme->classes) .'">' . $screenshot . '<div class="theme-info"><h3>' . $theme->info['name'] . ' ' . (isset($theme->info['version']) ? $theme->info['version'] : '') . $notes . '</h3><div class="theme-description">' . $description . '</div>';
+      $output .= '<div class="'. join(' ', $theme->classes) .'">' . $screenshot . '<div class="theme-info"><h3>' . check_plain($theme->info['name']) . ' ' . (isset($theme->info['version']) ? check_plain($theme->info['version']) : '') . $notes . '</h3><div class="theme-description">' . $description . '</div>';
 
       // Make sure to provide feedback on compatibility.
       if (!empty($theme->incompatible_core)) {