diff --git a/addons/website/controllers/form.py b/addons/website/controllers/form.py
index a354a514c5f..b5f95096c5f 100644
--- a/addons/website/controllers/form.py
+++ b/addons/website/controllers/form.py
@@ -141,7 +141,7 @@ class WebsiteForm(http.Controller):
             'meta': '',         # Add metadata if enabled
         }
 
-        authorized_fields = model.sudo()._get_form_writable_fields()
+        authorized_fields = model.with_user(SUPERUSER_ID)._get_form_writable_fields()
         error_fields = []
         custom_fields = []
 
@@ -239,7 +239,7 @@ class WebsiteForm(http.Controller):
         orphan_attachment_ids = []
         model_name = model.sudo().model
         record = model.env[model_name].browse(id_record)
-        authorized_fields = model.sudo()._get_form_writable_fields()
+        authorized_fields = model.with_user(SUPERUSER_ID)._get_form_writable_fields()
         for file in files:
             custom_field = file.field_name not in authorized_fields
             attachment_value = {