If you click "Login" on the upper right-hand side, you will go to a prompt. There in very fine print under the "username" text field you will see "Not a member? Sign up for an account." That's a link, and you can create an account there.
Everybody has permission :) as long as you have an account which you can create here https://jira.springframework.org/secure/Dashboard.jspa and create an issue in Spring Integration project.
I can do it, but if you do it then you'll be notified of its progress automatically.
Couldn't see it for looking ;-)
Raised as INT-1703