CVE-2021-43850: Discourse

Medium severity, CVSS 6.8. EPSS: 0.8% chance of exploitation in the next 30 days.

Discourse is an open source platform for community discussion. In affected versions admins users can trigger a Denial of Service attack via the `/message-bus/_diagnostics` path. The impact of this vulnerability is greater on multisite Discourse instances (where multiple forums are served from a single application server) where any admin user on any of the forums are able to visit the `/message-bus/_diagnostics` path. The problem has been patched. Please upgrade to 2.8.0.beta10 or 2.7.12. No workarounds for this issue exist.

Affected products

• Discourse Discourse: before 2.7.12 (fixed in 2.7.12); version 2.8.0 only

Published 2022-01-04. Last modified 2026-06-17.