CVE-2021-43840
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.
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Affected packages
Versions sourced from the GitHub Security Advisory.
| Package | Affected versions | Patched versions |
|---|---|---|
message_busRubyGems | < 3.3.7 | 3.3.7 |
Affected products
2- discourse/message_busv5Range: < 3.3.7
Patches
Vulnerability mechanics
References
5- github.com/discourse/message_bus/commit/9b6deee01ed474c7e9b5ff65a06bb0447b4db2banvdPatchThird Party AdvisoryWEB
- github.com/advisories/GHSA-xmgj-5fh3-xjmmghsaADVISORY
- github.com/discourse/message_bus/security/advisories/GHSA-xmgj-5fh3-xjmmnvdThird Party AdvisoryWEB
- nvd.nist.gov/vuln/detail/CVE-2021-43840ghsaADVISORY
- github.com/rubysec/ruby-advisory-db/blob/master/gems/message_bus/CVE-2021-43840.ymlghsaWEB
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