Issue #2099259 by Berdir: Missing default access for all taxonomy term fields

core/lib/Drupal/Core/Field/ChangedFieldItemList.php

+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Core\Field\ChangedFieldItemList.
+ */
+
+namespace Drupal\Core\Field;
+
+use Drupal\Core\Access\AccessResult;
+use Drupal\Core\Session\AccountInterface;
+
+/**
+ * Defines a item list class for changed fields.
+ */
+class ChangedFieldItemList extends FieldItemList {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function defaultAccess($operation = 'view', AccountInterface $account = NULL) {
+    // It is not possible to edit the changed field.
+    return AccessResult::allowedIf($operation !== 'edit');
+  }
+}

core/lib/Drupal/Core/Field/Plugin/Field/FieldType/ChangedItem.php

@@ -15,6 +15,7 @@
  *   label = @Translation("Last changed"),
  *   description = @Translation("An entity field containing a UNIX timestamp of when the entity has been last updated."),
  *   no_ui = TRUE,
+ *   list_class = "\Drupal\Core\Field\ChangedFieldItemList",
  *   constraints = {
  *     "ComplexData" = {"value" = {"EntityChanged" = {}}}
  *   }

core/modules/comment/src/CommentAccessControlHandler.php

@@ -74,7 +74,6 @@ protected function checkFieldAccess($operation, FieldDefinitionInterface $field_
 
       // No user can change read-only fields.
       $read_only_fields = array(
-        'changed',
         'hostname',
         'uuid',
         'cid',

core/modules/node/src/NodeAccessControlHandler.php

@@ -145,7 +145,7 @@ protected function checkFieldAccess($operation, FieldDefinitionInterface $field_
     }
 
     // No user can change read only fields.
-    $read_only_fields = array('changed', 'revision_timestamp', 'revision_uid');
+    $read_only_fields = array('revision_timestamp', 'revision_uid');
     if ($operation == 'edit' && in_array($field_definition->getName(), $read_only_fields, TRUE)) {
       return AccessResult::forbidden();
     }