CVE-2019-16770

mediumpriority · track · 31EPSS 0.020 · 81 %ileDEEUUS

grimoire priorityP3 · Track

Exploitable?

—

no known exploitation

Likely / severe?

2.01% (81st) EPSS

CVSS 5 · medium

Is it mine?

6 products

Check your exposure

Who says so?

5 sources

cnnvd · enisa_euvd · nvd · osv

EPSS · scored 2026-10-27

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.

remediations

Vendor fix, mitigation, or workaround guidance, as published by each source.

A vendor fix is available.

Fixedruby4.0-rubygem-puma-0:6.4.3-1.5.aarch64 as component of openSUSE Tumbleweedsuse_csaf
To install this SUSE Security Update use the SUSE recommended installation methods like YaST online_update or "zypper patch".
Fixedruby4.0-rubygem-puma-0:6.4.3-1.5.ppc64le as component of openSUSE Tumbleweedsuse_csaf
To install this SUSE Security Update use the SUSE recommended installation methods like YaST online_update or "zypper patch".
Fixedruby4.0-rubygem-puma-0:6.4.3-1.5.s390x as component of openSUSE Tumbleweedsuse_csaf
To install this SUSE Security Update use the SUSE recommended installation methods like YaST online_update or "zypper patch".
Fixedruby4.0-rubygem-puma-0:6.4.3-1.5.x86_64 as component of openSUSE Tumbleweedsuse_csaf
To install this SUSE Security Update use the SUSE recommended installation methods like YaST online_update or "zypper patch".

cvss

Technical severity, 0–10. One row per scoring source.

7.5

010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 5–7.5

v2.05mediumAV:N/AC:L/Au:N/C:N/I:N/A:Pprimary · NVD / NIST USexploitability 10 · impact 2.9

v3.17.5highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Hprimary · NVD / NIST USexploitability 3.9 · impact 3.6

v3.15.3mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Lsecondary · ENISA EU

v3.15.3mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Lsecondary · security-advisories@github.comexploitability 3.9 · impact 1.4

v3.15.3mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Lsecondary · OSV

v3.16.9mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:Usecondary · CVSS-BT (t0sche)

v3.17.5highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Hsecondary · SUSE Product Security

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-770USprimaryCWE-770US

affected products (6)

Products and version ranges known to be affected.

puma puma< 4.3.1 → 4.3.1enisa_euvdEU
debian debian linux= 9.0nvdUScpe:2.3:o:debian:debian_linux:*:*:*:*:*:*:*:*
puma puma3.0.0 → 3.12.2nvdUScpe:2.3:a:puma:puma:*:*:*:*:*:*:*:*
puma puma4.0.0 → 4.3.1nvdUScpe:2.3:a:puma:puma:*:*:*:*:*:*:*:*
RubyGems puma< 3.12.2osvUSpkg:gem/puma
RubyGems puma4.0.0 → 4.3.1osvUSpkg:gem/puma

advisories (2)

Vendor and ecosystem advisories describing this.

openSUSE-SU-2026:10357-1ruby4.0-rubygem-puma-6.4.3-1.5 on GA media2026-03-13csaf · suse_csafDE
ruby4.0-rubygem-puma-6.4.3-1.5 on GA media
GHSA-7xx3-m584-x994A poorly-behaved client could use keepalive requests to monopolize Puma's reactor and create a denial of service attack2019-12-05ghsa · osvUS
## Keepalive thread overload/DoS ### Impact 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. ### Patches This vulnerability is patched in Puma 4.3.1 and 3.12.2. ### Workarounds 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. ### For more information If you have any questions or comments about this advisory: * Open an issue at [puma](github.com/puma/puma).

also known as (3)

Other names and identifiers for this entity.

sources

Which sources assert this record, and when.

cnnvd enisa_euvd nvd osv suse_csaf NVD CVE.org MITRE

published 2019-12-05modified 2026-06-17

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+3265 more

references (19)

External citations — patches, advisories, analysis.

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