CVE-2020-11076

26

FAUCET Score

CVE-2020-11076 is a high-severity vulnerability affecting Puma (RubyGem) versions prior to 4.3.4 and 3.12.5, allowing an attacker to smuggle HTTP responses through an invalid transfer-encoding header. This network-exploitable flaw has a CVSS score of 7.5, indicating a high impact on integrity without requiring user interaction or privileges. While the vulnerability is patched in Puma 3.12.5 and 4.3.4, there is currently no evidence of active exploitation, publicly available exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage.

Impacted Technologies

Vendor	Product	Version(s)	CPE
		>= 3.0.0, < 3.12.6CPE matchmatch criteria	cpe:2.3:a:puma:puma::::::ruby::*
		>= 4.0.0, < 4.3.5CPE matchmatch criteria	cpe:2.3:a:puma:puma::::::ruby::*
		33CPE matchmatch criteria	cpe:2.3:o:fedoraproject:fedora:33:::::::*
		9.0CPE matchmatch criteria	cpe:2.3:o:debian:debian_linux:9.0:::::::*

CVSS Data

CVSS version used by this source: 3.1

7.5HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

NONE

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

NONE

Integrity Impact

HIGH

Availability Impact

NONE

Exploitability Score

3.9

Impact Score

3.6

CvssVersion

3.1

Exploit Intelligence

EPSS Score

3.98%

Probability of exploitation in next 30 days

EPSS Percentile

89.4%

Percentile rank of EPSS score among Peer Group

As of 2026-07-26

Model: v2026.06.15

This CVE's current EPSS score of 0.0398 is in the 81st percentile among its peer group of 51,485 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (5)

github_advisorypatch availablevia nvd_reference

rubygemspatch availablevia ghsa

Product: pumaFixed in: 3.12.5

rubygemspatch availablevia ghsa

Product: pumaFixed in: 4.3.4

redhatend of lifevia redhat_api

Product: CloudForms Management Engine 5Fixed in: rubygem-puma

redhatend of lifevia redhat_api

Product: Red Hat Storage 3Fixed in: rubygem-puma

Vendor Advisories (2)

rubygemsGHSA-x7jg-6pwg-fx5hhigh

HTTP Smuggling via Transfer-Encoding Header in Puma

redhatCVE-2020-11076Moderate

rubygem-puma: HTTP Smuggling via an invalid Transfer-Encoding Header

References

lists.opensuse.org / opensuse-security-announce/2020-07/msg00034.html

Mailing ListThird Party Advisory

lists.opensuse.org / opensuse-security-announce/2020-07/msg00038.html

Mailing ListThird Party Advisory

github.com / puma/puma/blob/master/History.md

Release Notes

github.com / puma/puma/commit/f24d5521295a2152c286abb0a45a1e1e2bd275bd

Patch

github.com / puma/puma/security/advisories/GHSA-x7jg-6pwg-fx5h

Third Party Advisory

lists.debian.org / debian-lts-announce/2020/10/msg00009.html

Mailing ListThird Party Advisory

lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/SKIY5H67GJIGJL6SMFWFLUQQQR3EMVPR