Invite bypasses user approval in Discourse

Discourse is an open source platform for community discussion. Prior to version 2.8.4 on the stable branch and 2.9.0beta5 on the beta and tests-passed branches, inviting users on sites that use single sign-on could bypass the must_approve_users check and invites by staff are always approved automatically. The issue is patched in Discourse version 2.8.4 on the stable branch and version 2.9.0.beta5 on the beta and tests-passed branches. As a workaround, disable invites or increase min_trust_level_to_allow_invite to reduce the attack surface to more trusted users.