CVE-2021-43850 Denial of Service in discourse
Admin users can trigger a Denial of Service attack via the message-bus diagnostics path, particularly affecting multisite Discourse instances.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2021-43850?
CVE-2021-43850 is a medium-severity denial of service vulnerability in Discourse Discourse, published on 4 Jan 2022. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Official description
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.
Weakness: CWE-20
Which versions are affected by CVE-2021-43850?
1 open source package ship an affected version, including discourse. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
discourse Bitnami | All versions | 2.7.12 |
Products include Discourse Discourse.
How do I fix CVE-2021-43850?
Upgrade discourse to 2.7.12 or later.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2021-43850 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2021-43850 exists.
Other vulnerabilities in Discourse Discourse
- CVE-2021-41163 RCE via malicious SNS subscription payload
- CVE-2022-36066 Discourse vulnerable to RCE via admins uploading maliciously zipped file
- CVE-2022-39356 Discourse user account takeover via email and invite link
- CVE-2023-22468 Discourse vulnerable to Cross-site Scripting in local oneboxes
- CVE-2026-27934 Discourse leaks private topic title and post excerpt via user action API endpoint
Sources
Also known as BIT-discourse-2021-43850, GHSA-59jr-pj65-qmvr.