diff -u b/core/modules/system/system.admin.inc b/core/modules/system/system.admin.inc
--- b/core/modules/system/system.admin.inc
+++ b/core/modules/system/system.admin.inc
@@ -267,7 +267,7 @@
     }
     $title = [
       '#type' => 'inline_template',
-      '#template' => '<span class="text"> {{ module_description }}</span>',
+      '#template' => '<span class="text">{{ module_description }}</span>',
       '#context' => ['module_description' => $module['description']],
     ];
     $details = array(
only in patch2:
unchanged:
--- a/core/modules/system/src/Form/ModulesListForm.php
+++ b/core/modules/system/src/Form/ModulesListForm.php
@@ -264,7 +264,7 @@ protected function buildRow(array $modules, Extension $module, $distribution) {
     $row['#required_by'] = array();
 
     $row['name']['#markup'] = $module->info['name'];
-    $row['description']['#markup'] = $this->t($module->info['description']);
+    $row['description']['#markup'] = $this->t(SafeMarkup::escape($module->info['description']));
     $row['version']['#markup'] = $module->info['version'];
 
     // Generate link for module's help page. Assume that if a hook_help()