This Rack middleware provides CSRF protection using the Sec-Fetch-Site header. It is inspired by Go's http.CrossOriginProtection which was introduced in Go 1.25. You can read about it in this article and find more information about the Sec-Fetch-Site header on MDN.
The middleware blocks cross-origin state-changing requests (POST, PUT, PATCH, DELETE) by first checking the Sec-Fetch-Site header, which is available in all modern browsers, and rejecting requests where the value is not same-origin or none. For older browsers that don't send Sec-Fetch-Site, it falls back to comparing the Origin header against the Host header, ensuring that only requests from the same origin can modify state. Safe methods (GET, HEAD, OPTIONS) are always allowed through, and requests without an Origin header are treated as same-origin to support non-browser clients.
Add this line to your application's Gemfile:
gem "super_good-csrf_protection"And then execute:
bundle installOr install it yourself with:
gem install super_good-csrf_protectionAdd the middleware to your Rack application:
require "super_good/csrf_protection"
use SuperGood::CSRFProtectionThe middleware rejects all non-GET requests without the Sec-Fetch-Site: same-origin header, providing protection against CSRF attacks.
After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.
To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and the created tag, and push the .gem file to rubygems.org.
Bug reports and pull requests are welcome on GitHub at https://github.com/SuperGoodSoft/csrf_protection. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the code of conduct.
The gem is available as open source under the terms of the MIT License.
Everyone interacting in the SuperGood::CSRFProtection project's codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.