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Fencer Vulns
medium 5.3

CVE-2019-16770 json

Potential DOS attack in Puma

published 2019-12-05 6 y ago modified 2026-07-08 4 mo ago also GHSA-7xx3-m584-x994 , EUVD-2019-0786

cvss
5.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
2.0%
EPSS 2.0% chance of exploitation in 30 days, percentile 81%
public exploits
0
none known

Summary

In Puma before versions 3.12.2 and 4.3.1, a poorly-behaved client could use keepalive requests to monopolize Puma's reactor and create a denial of service attack. If more keepalive connections to Puma are opened than there are threads available, additional connections will wait permanently if the attacker sends requests frequently enough. This vulnerability is patched in Puma 4.3.1 and 3.12.2.

Patch / fix

  • rubygems puma 3.12.2, 4.3.1
  • puma puma 4.3.1
  • puma Debian 14, Debian 13, Debian 12 3.12.0-4

debian advisories DEBIAN-CVE-2019-16770

  • rmt-server SLE Module for Server Applications 15 SP1, SLE Module for Public Cloud 15 SP1 2.6.5-3.18.1
  • rmt-server SLES for SAP 15, SLES 15-LTSS, SLE High Performance Computing 15-LTSS +1 more 2.6.5-3.34.1
  • rmt-server SLE Module for Server Applications 15 SP2, SLE Module for Public Cloud 15 SP2 2.6.5-3.3.1
  • rubygem-puma OpenStack Cloud Crowbar 9, OpenStack Cloud 7, OpenStack Cloud 6-LTSS 2.16.0-4.3.1
  • ardana-db OpenStack Cloud 9 9.0+git.1578936438.b9a9b95-3.16.1
  • ardana-mq OpenStack Cloud 9 9.0+git.1581024903.8e74867-3.10.1
  • ardana-tls OpenStack Cloud 9 9.0+git.1575296665.3fdfe45-3.9.1
  • crowbar-ha OpenStack Cloud Crowbar 9 6.0+git.1574286261.6fd1a34-3.13.2

suse advisories SUSE-SU-2020:3160-1SUSE-SU-2020:3147-1SUSE-SU-2020:3036-1SUSE-SU-2020:2060-1SUSE-SU-2020:0642-1SUSE-SU-2020:0640-1

  • rubygem-puma openSUSE Tumbleweed 6.4.3-1.5
  • rubygem-puma openSUSE Tumbleweed 6.4.3-1.3
  • rmt-server openSUSE Tumbleweed 2.6.13-1.1
  • rubygem-puma-4 openSUSE Tumbleweed 4.3.10-1.1
  • rubygem-puma openSUSE Tumbleweed 5.6.2-1.1
  • rubygem-puma-5 openSUSE Tumbleweed 5.6.5-1.1
  • ruby3.2-rubygem-puma openSUSE Tumbleweed 6.0.0-2.1
  • ruby3.2-rubygem-puma-5 openSUSE Tumbleweed 5.6.5-1.7

opensuse advisories openSUSE-SU-2026:10357-1openSUSE-SU-2025:15123-1openSUSE-SU-2024:10589-1openSUSE-SU-2024:11830-1openSUSE-SU-2024:11847-1openSUSE-SU-2024:12592-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2019-16770 updated cvss 0.0

rubygem-puma: keepalive requests from poorly-behaved client leads to denial of service

  • Red Hat CloudForms Management Engine 5 rubygem-puma Red Hat Software Collections rh-ror50-rubygem-puma Red Hat Storage 3 rubygem-puma
    affected: workaround, no fix planned “Reverse proxies in front of Puma could be configured to always allow less than X keepalive connections to a Puma cluster or process, where X is the number of threads configured in Puma's thread pool.”
  • Red Hat 3scale API Management Platform 2 rubygem-puma
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

2.01% chance of exploitation in the next 30 days, higher than 81% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:N/I:N/A:P
GitHub 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Affected packages

ecosystem package affected fixed in
rubygems puma
<3.12.2
>=4.0.0, <4.3.1
3.12.2
4.3.1

Affected products

  • puma puma

Classification

Weakness
  • CWE-770 Allocation of Resources Without Limits or Throttling

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.