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CVE-2024-21647

23
FAUCET Score

CVE-2024-21647 is a high-severity vulnerability affecting Puma, a web server for Ruby/Rack applications, specifically versions prior to 6.4.2 and 5.6.8. This flaw, categorized as CWE-444 (Inaccurate Parsing of HTTP Request), allows for HTTP request smuggling due to incorrect parsing of chunked transfer encoding bodies. An unauthenticated attacker can exploit this remotely with low complexity to cause unbounded resource consumption (CPU, network bandwidth), leading to a denial-of-service. There is currently no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage.

Impacted Technologies

VendorProductVersion(s)CPE
< 5.6.8CPE matchmatch criteria
cpe:2.3:a:puma:puma:*:*:*:*:*:ruby:*:*
>= 6.0.0, < 6.4.2CPE matchmatch criteria
cpe:2.3:a:puma:puma:*:*:*:*:*:ruby:*:*

CVSS Data

CVSS version used by this source: 3.1

5.9MEDIUM

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

Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
2.2
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.96%
Probability of exploitation in next 30 days
EPSS Percentile
57.8%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0096 is in the 32nd percentile among its peer group of 51,506 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

No media coverage found for this CVE.

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 (4)

github_advisorypatch availablevia nvd_reference
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Satellite 6.15 for RHEL 8Fixed in: rubygem-puma-0:6.4.2-1.el8sat
View patch
rubygemspatch availablevia ghsa
Product: pumaFixed in: 6.4.2
rubygemspatch availablevia ghsa
Product: pumaFixed in: 5.6.8

Vendor Advisories (2)

rubygemsGHSA-c2f4-cvqm-65w2medium

Puma HTTP Request/Response Smuggling vulnerability

Jan 8, 2024
redhatCVE-2024-21647Important

rubygem-puma: HTTP request smuggling when parsing chunked Transfer-Encoding Bodies

Jan 8, 2024

References

lists.debian.org / debian-lts-announce/2024/11/msg00004.html
github.com / puma/puma/commit/5fc43d73b6ff193325e657a24ed76dec79133e93
Patch
github.com / puma/puma/security/advisories/GHSA-c2f4-cvqm-65w2
Vendor Advisory