Discourse may allow exposure of hidden tags in the subject of notification emails

Discourse is an open-source discussion platform. Prior to version 2.8.13 of the stable branch and version 2.9.0.beta14 of the beta and tests-passed branches, unauthorized users may learn of the existence of hidden tags and that they have been applied to topics that they have access to. This issue is patched in version 2.8.13 of the stable branch and version 2.9.0.beta14 of the beta and tests-passed branches. As a workaround, use the disable_email site setting to disable all emails to non-staff users.