Rails 4 ActionController::InvalidAuthenticityToken with multiple subdomains - ruby-on-rails

Question

Before let me say that I search google and a lot of posts here at Stackoverflow, but nothing was able to give a solution for my problem. for this, I am creating a new post.
I am creating an application with two sub-domains: account.psantos.dev and app.psantos.dev.
At: config/initializers/session_store.rbI have:
Rails.application.config.session_store :cookie_store, key: '_psantos.co.ao_session', domain: 'psantos.dev'
And I have the following structure folders:
- app
-- controllers
--- app1
---- welcome_controller.rb
--- account
---- welcome_controller.rb
--views
--- layout
---- app1.html.erb
---- account.html.erb
--- app1
---- welcome
----- index.html.erb
--- account
---- welcome
----- index.html.erb
at: app/views/layout/app1.html.erb (http://app1.psantos.dev) I have the following line:
<li><%= "Logout", account_sign_out_url, method: :delete %></li>
When I click this Link (that will go to: http://account.psantos.dev), I got the following error:
ActionController::InvalidAuthenticityToken at /sign_out
ActionController::InvalidAuthenticityToken
on both layout files (app1.html.erb and account.html.erb) I have this line before <\head > tag :
<%= csrf_meta_tags %>
how can I solve this problem?
Update: relevant log
Started GET "/" for 127.0.0.1 at 2015-08-08 12:37:03 +0100 Processing
by APP1::WelcomeController#index as HTML Parameters:
{"subdomain"=>"app1"} Rendered app1/welcome/index.html.erb within
layouts/app1 (0.4ms) [1m[35mEntity Load (0.3ms)[0m SELECT
"entities".* FROM "entities" WHERE "entities"."user_token" = $1 LIMIT
1 [["user_token", "xxxxxxxxxxxxxxxxxxxx"]] Completed 200 OK in 43ms
(Views: 42.0ms | ActiveRecord: 0.3ms)
Started DELETE "/sign_out" for 127.0.0.1 at 2015-08-08 12:37:05 +0100
Processing by Account::SessionsController#destroy as HTML
Parameters: {"subdomain"=>"account"} Can't verify CSRF token
authenticity Completed 422 Unprocessable Entity in 1ms (ActiveRecord:
0.0ms)
ActionController::InvalidAuthenticityToken -
ActionController::InvalidAuthenticityToken: actionpack (4.2.3)
lib/action_controller/metal/request_forgery_protection.rb:181:in
`handle_unverified_request' actionpack (4.2.3)
lib/action_controller/metal/request_forgery_protection.rb:209:in
`handle_unverified_request' actionpack (4.2.3)
lib/action_controller/metal/request_forgery_protection.rb:204:in
`verify_authenticity_token' activesupport (4.2.3)
lib/active_support/callbacks.rb:430:in `block in make_lambda'
activesupport (4.2.3) lib/active_support/callbacks.rb:143:in `block in
halting_and_conditional' activesupport (4.2.3)
lib/active_support/callbacks.rb:502:in `block in call' activesupport
(4.2.3) lib/active_support/callbacks.rb:502:in `call'

Answer 1

Now it's impossible to do :delete request to subdomain.
There is an vulnerability in jquery-ujs and jquery-rails that can be used to bypass CSP protections and allows attackers to send CSRF tokens to attacker domains. This vulnerability has been assigned the CVE identifier CVE-2015-1840. Versions Affected: All. Not affected: Applications which don't use jquery-ujs or jquery-rails. Fixed Versions: jquery-rails versions 4.0.4 and 3.1.3 and jquery-ujs 1.0.4. Impact ------ In the scenario where an attacker might be able to control the href attribute of an anchor tag or the action attribute of a form tag that will trigger a POST action, the attacker can set the href or action to " https://attacker.com" (note the leading space) that will be passed to JQuery, who will see this as a same origin request, and send the user's CSRF token to the attacker domain.
This is commit to jquery-ujs:
You can read more here