Discourse DoS via 2FA and Security Key Names

Discourse is an open-source discussion platform. Prior to version 3.1.1 of the stable branch and version 3.2.0.beta1 of the beta and tests-passed branches, a malicious user could add a 2FA or security key with a carefully crafted name to their account and cause a denial of service for other users. The issue is patched in version 3.1.1 of the stable branch and version 3.2.0.beta1 of the beta and tests-passed branches. There are no known workarounds.