Discourse Topic Creation Page Allows iFrame Tag without Restrictions

Discourse is an open source discussion platform. Prior to version 3.0.4 of the stable branch and version 3.1.0.beta5 of the beta and tests-passed branches, the lack of restrictions on the iFrame tag makes it easy for an attacker to exploit the vulnerability and hide subsequent comments from other users. This issue is patched in version 3.0.4 of the stable branch and version 3.1.0.beta5 of the beta and tests-passed branches. There are no known workarounds.