CVE-2021-43850

Name: CVE-2021-43850
Creator: NVD / NIST
Published: 2022-01-04T20:15:07.667+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 6.8/10EPSS 0.83%

Last modified Jun 17, 2026

CVE-2021-43850 is a medium-severity vulnerability rated 6.8/10 on the CVSS scale. 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. EPSS estimates a 0.83% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1

6.8/10

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:N/I:N/A:H

EPSS Probability

0.83%

52.8th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-20

Affected Software

Vendor	Product	Versions	Update
Discourse	Discourse	< 2.7.12	—
Discourse	Discourse	2.8.0	Beta1

References

https://github.com/discourse/discourse/commit/7a8ec129fb54f188b2da6588c9d24d3a36eb0d39Patch, Third Party Advisory
https://github.com/discourse/discourse/security/advisories/GHSA-59jr-pj65-qmvrExploit, Third Party Advisory
https://github.com/discourse/discourse/commit/7a8ec129fb54f188b2da6588c9d24d3a36eb0d39Patch, Third Party Advisory
https://github.com/discourse/discourse/security/advisories/GHSA-59jr-pj65-qmvrExploit, Third Party Advisory

Timeline

Published: Jan 4, 2022
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-43850?

How severe is CVE-2021-43850?

CVE-2021-43850 has a CVSS score of 6.8/10 (MEDIUM severity). The EPSS model estimates a 0.83% probability of exploitation in the next 30 days.

How do I fix CVE-2021-43850?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-43850?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST