diff --git a/app/controllers/attachments_controller.rb b/app/controllers/attachments_controller.rb
index 5fc81c5d5..46fa024db 100644
--- a/app/controllers/attachments_controller.rb
+++ b/app/controllers/attachments_controller.rb
@@ -5,6 +5,7 @@ class AttachmentsController < ApplicationController
   before_action :require_login, :check_auth, except: [:show]
   before_action :find_file, only: %i[show destroy]
   before_action :attachment_candown, only: [:show]
+  skip_before_action :check_sign, only: [:show]
 
   include ApplicationHelper