Vulnerability Description
Puma is a concurrent HTTP 1.1 server for Ruby/Rack applications. The fix for CVE-2019-16770 was incomplete. The original fix only protected existing connections that had already been accepted from having their requests starved by greedy persistent-connections saturating all threads in the same process. However, new connections may still be starved by greedy persistent-connections saturating all threads in all processes in the cluster. A `puma` server which received more concurrent `keep-alive` connections than the server had threads in its threadpool would service only a subset of connections, denying service to the unserved connections. This problem has been fixed in `puma` 4.3.8 and 5.3.1. Setting `queue_requests false` also fixes the issue. This is not advised when using `puma` without a reverse proxy, such as `nginx` or `apache`, because you will open yourself to slow client attacks (e.g. slowloris). The fix is very small and a git patch is available for those using unsupported versions of Puma.
CVSS Score
HIGH
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Puma | Puma | < 4.3.8 |
| Debian | Debian Linux | 10.0 |
Related Weaknesses (CWE)
References
- https://gist.github.com/nateberkopec/4b3ea5676c0d70cbb37c82d54be25837PatchThird Party Advisory
- https://github.com/puma/puma/security/advisories/GHSA-q28m-8xjw-8vr5PatchThird Party Advisory
- https://github.com/puma/puma/security/policyThird Party Advisory
- https://lists.debian.org/debian-lts-announce/2022/08/msg00015.htmlMailing ListThird Party Advisory
- https://rubygems.org/gems/pumaProductThird Party Advisory
- https://security.gentoo.org/glsa/202208-28Third Party Advisory
- https://gist.github.com/nateberkopec/4b3ea5676c0d70cbb37c82d54be25837PatchThird Party Advisory
- https://github.com/puma/puma/security/advisories/GHSA-q28m-8xjw-8vr5PatchThird Party Advisory
- https://github.com/puma/puma/security/policyThird Party Advisory
- https://lists.debian.org/debian-lts-announce/2022/08/msg00015.htmlMailing ListThird Party Advisory
- https://rubygems.org/gems/pumaProductThird Party Advisory
- https://security.gentoo.org/glsa/202208-28Third Party Advisory
FAQ
What is CVE-2021-29509?
CVE-2021-29509 is a vulnerability with a CVSS score of 7.5 (HIGH). Puma is a concurrent HTTP 1.1 server for Ruby/Rack applications. The fix for CVE-2019-16770 was incomplete. The original fix only protected existing connections that had already been accepted from hav...
How severe is CVE-2021-29509?
CVE-2021-29509 has been rated HIGH with a CVSS base score of 7.5/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2021-29509?
Check the references section above for vendor advisories and patch information. Affected products include: Puma Puma, Debian Debian Linux.