diff --git a/src/Forms/Form.php b/src/Forms/Form.php
index 1c62887369b..d271d701d6d 100644
--- a/src/Forms/Form.php
+++ b/src/Forms/Form.php
@@ -502,7 +502,7 @@ public function getSessionValidationResult()
     {
         $resultData = $this->getSession()->get("FormInfo.{$this->FormName()}.result");
         if (isset($resultData)) {
-            return unserialize($resultData ?? '');
+            return unserialize($resultData ?? '', ['allowed_classes' => [ValidationResult::class]]);
         }
         return null;
     }