Puma's Keepalive Connections Causing Denial Of Service
Published May 11, 2021 · Updated Nov 3, 2026
Original summary
Normalized public record · Updated Nov 3, 2026
Puma's Keepalive Connections Causing Denial Of Service
Publisher and source text is retained separately from QFinch interpretation.
QFinch assessment
This vulnerability is related to [CVE-2019-16770](https://github.com/puma/puma/security/advisories/GHSA-7xx3-m584-x994).
Potential impact
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.
Evidence: public source recordsAffected products
| Affected package, product or range | Fix status |
|---|---|
| Consult the referenced vendor advisory for affected versions. | Consult source advisory |
Matching a version is only one part of assessing exposure. QFinch has not assessed your environment on this public page.
Remediation
Apply the vendor-supported fixed release or mitigation, then verify the affected component is no longer reachable.
- Confirm the affected product and reachable code path exist in your environment.
- Apply the vendor-supported patch or mitigation from the primary advisory.
- Rescan the exact deployed revision and retain verification evidence.
Evidence coverage
- SSVC priority
- MEDIUM
- Confidence
- Not available
- Aliases
- None reported
Scores appear only when corresponding evidence exists. Missing data is never interpreted as zero risk.
Sources and record history
- Security advisory ↗
- gist.github.com ↗
- Source repository ↗
- rubygems.org ↗
- GLSA-202208-28 ↗
- [debian-lts-announce] 20220827 [SECURITY] [DLA 3083-1] puma security update ↗
Record history
Published May 11, 2021 · Last refreshed Nov 3, 2026