Discourse vulnerable to Cross-site Scripting - user name displayed on post

Discourse is an open-source discussion platform. Prior to version 3.0.1 of the stable branch and version 3.1.0.beta2 of the beta and tests-passed branches, a maliciously crafted URL can be included in a user's full name field to to carry out cross-site scripting attacks on sites with a disabled or overly permissive CSP (Content Security Policy). Discourse's default CSP prevents this vulnerability. The vulnerability is patched in version 3.0.1 of the stable branch and version 3.1.0.beta2 of the beta and tests-passed branches. As a workaround, enable and/or restore your site's CSP to the default one provided with Discourse.