CVE-2021-29509
Puma is a concurrent HTTP 1.1 server for Ruby/Rack applications.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (1.60%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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 3.1
- 7.5 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- EPSS
- 1.60% probability · 74th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-400, CWE-667
- Affected
- puma/puma · debian/debian linux
- Source
- security-advisories@github.com
References
- https://gist.github.com/nateberkopec/4b3ea5676c0d70cbb37c82d54be25837Patch, Third Party Advisory
- https://github.com/puma/puma/security/advisories/GHSA-q28m-8xjw-8vr5Patch, Third Party Advisory
- https://github.com/puma/puma/security/policyThird Party Advisory
- https://lists.debian.org/debian-lts-announce/2022/08/msg00015.htmlMailing List, Third Party Advisory
- https://rubygems.org/gems/pumaProduct, Third Party Advisory
- https://security.gentoo.org/glsa/202208-28Third Party Advisory
- https://gist.github.com/nateberkopec/4b3ea5676c0d70cbb37c82d54be25837Patch, Third Party Advisory
- https://github.com/puma/puma/security/advisories/GHSA-q28m-8xjw-8vr5Patch, Third Party Advisory
- https://github.com/puma/puma/security/policyThird Party Advisory
- https://lists.debian.org/debian-lts-announce/2022/08/msg00015.htmlMailing List, Third Party Advisory
- https://rubygems.org/gems/pumaProduct, Third Party Advisory
- https://security.gentoo.org/glsa/202208-28Third Party Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.