CVE-2020-11076

mediumpriority · track · 41EPSS 0.041 · 91 %ileexploit · PoCDEEURUUS

grimoire priorityP1 · Urgent

Exploitable?

Public exploit

1 exploit · PoC

Likely / severe?

4.09% (91st) EPSS

CVSS 5 · medium

Is it mine?

13 products

Check your exposure

Who says so?

6 sources

cnnvd · enisa_euvd · fstec_bdu · nvd

EPSS · scored 2026-10-27

In Puma (RubyGem) before 4.3.4 and 3.12.5, an attacker could smuggle an HTTP response, by using an invalid transfer-encoding header. The problem has been fixed in Puma 3.12.5 and Puma 4.3.4.

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:P/A:Nprimary · 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:H/A:Nprimary · NVD / NIST USexploitability 3.9 · impact 3.6

v3.17.5highAV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:Nsecondary · FSTEC (BDU) RU

v3.17.5highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:Nsecondary · ENISA EU

v3.17.5highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:Nsecondary · security-advisories@github.comexploitability 3.9 · impact 3.6

v3.17.5highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:Nsecondary · OSV

v3.17.1highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N/E:Psecondary · CVSS-BT (t0sche)

v3.16.8mediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:H/A:Nsecondary · SUSE Product Security

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-444USprimaryCWE-444USCWE-444US

exploits (1)

Public proof-of-concept and weaponised exploit code.

dentarg/cougarPuma, CVE-2020-11076 and CVE-2020-11077PoC · poc_in_github

affected products (13)

Products and version ranges known to be affected.

puma puma≤ < 3.12.5enisa_euvdEU
puma puma4.0.0, → 4.3.4enisa_euvdEU
Novell Inc. OpenSUSE Leap≤ 15.2fstec_bduRU
Novell Inc. OpenSUSE Leap≤ 15.1fstec_bduRU
АО «НППКТ» ОСОН ОСнова Оnyx≤ 2.1fstec_bduRU
Сообщество свободного программного обеспечения Puma≤ 4.3.4fstec_bduRU
Сообщество свободного программного обеспечения Puma≤ 3.12.5fstec_bduRU
debian debian linux= 9.0nvdUScpe:2.3:o:debian:debian_linux:*:*:*:*:*:*:*:*
fedoraproject fedora= 33nvdUScpe:2.3:o:fedoraproject:fedora:*:*:*:*:*:*:*:*
puma puma3.0.0 → 3.12.6nvdUScpe:2.3:a:puma:puma:*:*:*:*:*:*:*:*
puma puma4.0.0 → 4.3.5nvdUScpe:2.3:a:puma:puma:*:*:*:*:*:*:*:*
RubyGems puma< 3.12.5osvUSpkg:gem/puma
RubyGems puma4.0.0 → 4.3.4osvUSpkg: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-x7jg-6pwg-fx5hHTTP Smuggling via Transfer-Encoding Header in Puma2020-05-22ghsa · osvUS
### Impact By using an invalid transfer-encoding header, an attacker could [smuggle an HTTP response.](https://portswigger.net/web-security/request-smuggling) Originally reported by @ZeddYu, who has our thanks for the detailed report. ### Patches The problem has been fixed in Puma 3.12.5 and Puma 4.3.4. ### For more information If you have any questions or comments about this advisory: * Open an issue in [Puma](https://github.com/puma/puma) * See our [security policy](https://github.com/puma/puma/security/policy)

also known as (4)

Other names and identifiers for this entity.

sources

Which sources assert this record, and when.

cnnvd enisa_euvd fstec_bdu nvd osv suse_csaf NVD CVE.org MITRE

published 2020-05-22modified 2026-06-17

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+548 more

references (29)

External citations — patches, advisories, analysis.

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