Under certain circumstances response bodies will not be closed, for example a bug in a webserver or a bug in a Rack middleware. In the event a response is not notified of a
ActionDispatch::Executor will not know to reset thread local state for the next request. This can lead to data being leaked to subsequent requests, especially when interacting with
Upgrading to the FIXED versions of Rails will ensure mitigation of this issue even in the context of a buggy webserver or middleware implementation.
This has been fixed in Rails 220.127.116.11, 18.104.22.168, 22.214.171.124, and 126.96.36.199.
Upgrading is highly recommended, but to work around this problem the following middleware can be used:
class GuardedExecutor < ActionDispatch::Executor def call(env) ensure_completed! super end private def ensure_completed! @executor.new.complete! if @executor.active? end end # Ensure the guard is inserted before ActionDispatch::Executor Rails.application.configure do config.middleware.swap ActionDispatch::Executor, GuardedExecutor, executor end