Discourse user account takeover via email and invite link

Discourse is a platform for community discussion. Users who receive an invitation link that is not scoped to a single email address can enter any non-admin user's email and gain access to their account when accepting the invitation. All users should upgrade to the latest version. A workaround is temporarily disabling invitations with SiteSetting.max_invites_per_day = 0 or scope them to individual email addresses.