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CVE-2023-40175

29
FAUCET Score

CVE-2023-40175 is a critical HTTP request smuggling vulnerability affecting Puma web server versions prior to 6.3.1 and 5.6.7. This flaw stems from incorrect parsing of chunked transfer encoding bodies or zero-length Content-Length headers, allowing attackers to manipulate HTTP requests. With a CVSS score of 9.8 (Critical), it presents a high risk of compromise (C:H/I:H/A:H) due to its network-based attack vector and low attack complexity. While there is no known active exploitation or public exploit code (Metasploit, Nuclei, ExploitDB), the vulnerability has garnered some community discussion, with users advised to upgrade immediately as there are no workarounds.

Impacted Technologies

VendorProductVersion(s)CPE
< 5.6.7CPE matchmatch criteria
cpe:2.3:a:puma:puma:*:*:*:*:*:ruby:*:*
>= 6.0.0, < 6.3.1CPE matchmatch criteria
cpe:2.3:a:puma:puma:*:*:*:*:*:ruby:*:*

CVSS Data

CVSS version used by this source: 3.1

7.3HIGH

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
LOW
Integrity Impact
LOW
Availability Impact
LOW
Exploitability Score
3.9
Impact Score
3.4
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.74%
Probability of exploitation in next 30 days
EPSS Percentile
50.8%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0074 is in the 34th percentile among its peer group of 36,862 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (7)

github_advisorypatch availablevia nvd_reference
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Satellite 6.14 for RHEL 8Fixed in: rubygem-puma-0:6.3.1-1.el8sat
View patch
rubygemspatch availablevia ghsa
Product: pumaFixed in: 6.3.1
rubygemspatch availablevia ghsa
Product: pumaFixed in: 5.6.7
redhatno patchvia redhat_api
Product: Red Hat 3scale API Management Platform 2Fixed in: 3scale-amp-zync-container
redhatno patchvia redhat_api
Product: Red Hat Satellite 6Fixed in: tfm-rubygem-puma
redhatend of lifevia redhat_api
Product: Red Hat Storage 3Fixed in: rubygem-puma

Vendor Advisories (2)

rubygemsGHSA-68xg-gqqm-vgj8critical

Puma HTTP Request/Response Smuggling vulnerability

Aug 18, 2023
redhatCVE-2023-40175Moderate

rubygem-puma: HTTP request smuggling when parsing chunked transfer encoding bodies and zero-length content-length headers

Aug 18, 2023

References

github.com / puma/puma/commit/690155e7d644b80eeef0a6094f9826ee41f1080a
Patch
github.com / puma/puma/security/advisories/GHSA-68xg-gqqm-vgj8
Vendor Advisory