Vulnerability Description
message_bus is a messaging bus for Ruby processes and web clients. In versions prior to 3.3.7 users who deployed message bus with diagnostics features enabled (default off) are vulnerable to a path traversal bug, which could lead to disclosure of secret information on a machine if an unintended user were to gain access to the diagnostic route. The impact is also greater if there is no proxy for your web application as the number of steps up the directories is not bounded. For deployments which uses a proxy, the impact varies. For example, If a request goes through a proxy like Nginx with `merge_slashes` enabled, the number of steps up the directories that can be read is limited to 3 levels. This issue has been patched in version 3.3.7. Users unable to upgrade should ensure that MessageBus::Diagnostics is disabled.
CVSS Score
MEDIUM
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Discourse | Message Bus | < 3.3.7 |
Related Weaknesses (CWE)
References
- https://github.com/discourse/message_bus/commit/9b6deee01ed474c7e9b5ff65a06bb044PatchThird Party Advisory
- https://github.com/discourse/message_bus/security/advisories/GHSA-xmgj-5fh3-xjmmThird Party Advisory
- https://github.com/discourse/message_bus/commit/9b6deee01ed474c7e9b5ff65a06bb044PatchThird Party Advisory
- https://github.com/discourse/message_bus/security/advisories/GHSA-xmgj-5fh3-xjmmThird Party Advisory
FAQ
What is CVE-2021-43840?
CVE-2021-43840 is a vulnerability with a CVSS score of 4.4 (MEDIUM). message_bus is a messaging bus for Ruby processes and web clients. In versions prior to 3.3.7 users who deployed message bus with diagnostics features enabled (default off) are vulnerable to a path tr...
How severe is CVE-2021-43840?
CVE-2021-43840 has been rated MEDIUM with a CVSS base score of 4.4/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2021-43840?
Check the references section above for vendor advisories and patch information. Affected products include: Discourse Message Bus.