Incorrect handling of certain characters passed to the redirection functionality in Rails can lead to a single-click XSS vulnerability.

Overview Incorrect handling of certain characters passed to the redirection functionality in Rails can lead to a single-click XSS vulnerability across web applications. This has been tested on the latest version of Rails as of today (7.0.4.3).

class ApplicationController < ActionController::Base
  def vuln
    redirect_to params[:redirect_url], allow_other_host: true
  end
end