CVE-2021-43840
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…
Does this matter?
Lower severity and a low EPSS score (1.87%). Track it; it rarely justifies an emergency change on its own.
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 3.1
- 6.5 MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
- EPSS
- 1.87% probability · 78th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-22
- Affected
- discourse/message bus
- Source
- security-advisories@github.com
References
- https://github.com/discourse/message_bus/commit/9b6deee01ed474c7e9b5ff65a06bb0447b4db2baPatch, Third Party Advisory
- https://github.com/discourse/message_bus/security/advisories/GHSA-xmgj-5fh3-xjmmThird Party Advisory
- https://github.com/discourse/message_bus/commit/9b6deee01ed474c7e9b5ff65a06bb0447b4db2baPatch, Third Party Advisory
- https://github.com/discourse/message_bus/security/advisories/GHSA-xmgj-5fh3-xjmmThird Party Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.