diff --git a/CHANGELOG.md b/CHANGELOG.md
index cfc2f70d..963f9574 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,6 +10,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 ### Fixed
 
 - Fix mandatory fields of a block hidden by its display conditions blocking the save of an item
+- Fix fields values updates not applying the expected checks in some cases
 - Fix ticket observers being able to edit and save additional fields they are not allowed to modify
 
 ## [1.25.0] - 2026-10-06
diff --git a/inc/abstractcontainerinstance.class.php b/inc/abstractcontainerinstance.class.php
index 549e67b4..45577142 100644
--- a/inc/abstractcontainerinstance.class.php
+++ b/inc/abstractcontainerinstance.class.php
@@ -34,6 +34,27 @@ abstract class PluginFieldsAbstractContainerInstance extends CommonDBChild
 
     public static string $items_id = 'items_id';
 
+    // Values are only written through the parent item or the container form
+    public static function canCreate(): bool
+    {
+        return false;
+    }
+
+    public static function canUpdate(): bool
+    {
+        return false;
+    }
+
+    public static function canDelete(): bool
+    {
+        return false;
+    }
+
+    public static function canPurge(): bool
+    {
+        return false;
+    }
+
     /**
      * This function relies on the static property `static::$plugins_forward_entity`,
      * which should be populated using the following method (from setup):
diff --git a/tests/Units/ContainerItemRightTest.php b/tests/Units/ContainerItemRightTest.php
index 3f60d44b..fa4a8be6 100644
--- a/tests/Units/ContainerItemRightTest.php
+++ b/tests/Units/ContainerItemRightTest.php
@@ -166,6 +166,53 @@ public function testShowDomContainerRendersReadOnlyFieldsWithoutUpdateRight(): v
         );
     }
 
+    public function testContainerValuesCanOnlyBeWrittenThroughContainer(): void
+    {
+        $this->login();
+        $entity_id = getItemByTypeName(Entity::class, '_test_root_entity', true);
+        $this->setEntity($entity_id, true);
+
+        $container = $this->createFieldContainer([
+            'label'        => 'Tab container ' . $this->getUniqueString(),
+            'type'         => 'tab',
+            'itemtypes'    => [Computer::class],
+            'is_active'    => 1,
+            'entities_id'  => $entity_id,
+            'is_recursive' => 1,
+        ]);
+        $field = $this->createField([
+            'label'                                     => 'Tab field',
+            'type'                                      => 'text',
+            PluginFieldsContainer::getForeignKeyField() => $container->getID(),
+            'ranking'                                   => 1,
+            'is_active'                                 => 1,
+            'is_readonly'                               => 0,
+        ]);
+        $computer = $this->createItem(Computer::class, [
+            'name'        => 'Computer ' . $this->getUniqueString(),
+            'entities_id' => $entity_id,
+        ]);
+
+        $this->assertTrue($container->updateFieldsValues([
+            'plugin_fields_containers_id' => $container->getID(),
+            'itemtype'                    => Computer::class,
+            'items_id'                    => $computer->getID(),
+            $field->fields['name']        => 'value',
+        ], Computer::class, false));
+
+        $classname = PluginFieldsContainer::getClassname(Computer::class, $container->fields['name']);
+        $values    = new $classname();
+        $this->assertTrue($values->getFromDBByCrit(['items_id' => $computer->getID()]));
+        $this->assertSame('value', $values->fields[$field->fields['name']]);
+
+        $this->assertTrue($values->can($values->getID(), READ));
+        $this->assertFalse($values->can($values->getID(), UPDATE));
+        $this->assertFalse($values->can($values->getID(), DELETE));
+        $this->assertFalse($values->can($values->getID(), PURGE));
+        $input = ['itemtype' => Computer::class, 'items_id' => $computer->getID()];
+        $this->assertFalse($values->can(-1, CREATE, $input));
+    }
+
     private function renderDomContainer(int $containers_id, Computer $computer): string
     {
         ob_start();