Inconsistent Interpretation of HTTP Requests in puma
Puma is a Ruby/Rack web server built for parallelism. Prior to versions 6.3.1 and 5.6.7, puma exhibited incorrect behavior when parsing chunked transfer encoding bodies and zero-length Content-Length headers in a way that allowed HTTP request smuggling. Severity of this issue is highly dependent on the nature of the web site using puma is. This could be caused by either incorrect parsing of trailing fields in chunked transfer encoding bodies or by parsing of blank/zero-length Content-Length headers. Both issues have been addressed and this vulnerability has been fixed in versions 6.3.1 and 5.6.7. Users are advised to upgrade. There are no known workarounds for this vulnerability.
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for the hundreds of thousands of vulnerabilities in the database; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.
We use this product, ask for help- Published
- Aug 18, 2023
- Updated
- Jun 17, 2026
- EPSS
- 0.8% · 56th percentile
- CWE
- CWE-444
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Report tools
Action score
39
Monitor
Low priority for now.
- CVSS
- 39 / 40 · 9.8 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.8%
CISA SSVC decision
- Exploitation
- none
- Automatable
- yes
- Technical impact
- partial
Vulnrichment: CISA's decision-tree inputs.
CNA vs NVD score
- NVD
- 9.8
- CNA · GitHub_M
- 7.3
- 2.5 point gap
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.
Affected systems
| Vendor | Product | CPE |
|---|---|---|
| puma | puma | cpe:2.3:a:puma:puma |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- puma pumabefore 5.6.7
- puma puma6.0.0 and later · before 6.3.1
Versions reported by the vendor
Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.
puma puma
- < 5.6.7, >= 6.0.0, < 6.3.1affected
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Debian:12 | puma | before 5.6.5-3+deb12u1 | 5.6.5-3+deb12u1 |
| Debian:13 | puma | before 5.6.7-1 | 5.6.7-1 |
| Red Hat:satellite_capsule:6.14::el8 | mosquitto | before 0:2.0.17-1.el8sat | 0:2.0.17-1.el8sat |
| Red Hat:satellite_capsule:6.14::el8 | mosquitto-debuginfo | before 0:2.0.17-1.el8sat | 0:2.0.17-1.el8sat |
| Red Hat:satellite_capsule:6.14::el8 | mosquitto-debugsource | before 0:2.0.17-1.el8sat | 0:2.0.17-1.el8sat |
| Red Hat:satellite_capsule:6.14::el8 | puppet-agent | before 0:7.27.0-1.el8sat | 0:7.27.0-1.el8sat |
| Red Hat:satellite_capsule:6.14::el8 | puppetserver | before 0:7.14.0-1.el8sat | 0:7.14.0-1.el8sat |
| Red Hat:satellite:6.14::el8 | candlepin | before 0:4.3.11-1.el8sat | 0:4.3.11-1.el8sat |
| Red Hat:satellite:6.14::el8 | candlepin-selinux | before 0:4.3.11-1.el8sat | 0:4.3.11-1.el8sat |
| Red Hat:satellite:6.14::el8 | rubygem-grpc | before 0:1.58.0-1.el8sat | 0:1.58.0-1.el8sat |
| Red Hat:satellite:6.14::el8 | rubygem-puma | before 0:6.3.1-1.el8sat | 0:6.3.1-1.el8sat |
| Red Hat:satellite:6.14::el8 | rubygem-puma-debuginfo | before 0:6.3.1-1.el8sat | 0:6.3.1-1.el8sat |
| Red Hat:satellite:6.14::el8 | rubygem-puma-debugsource | before 0:6.3.1-1.el8sat | 0:6.3.1-1.el8sat |
| Red Hat:satellite:6.14::el8 | rubygem-sidekiq | before 0:6.5.12-1.el8sat | 0:6.5.12-1.el8sat |
| RubyGems | puma | from 6.0.0 · before 6.3.1 | 6.3.1 |
| RubyGems | puma | before 5.6.7 | 5.6.7 |
| SUSE:Linux Enterprise High Availability Extension 15 SP1 | rubygem-puma | before 4.3.12-150000.3.12.1 | 4.3.12-150000.3.12.1 |
| SUSE:Linux Enterprise High Availability Extension 15 SP1 | rubygem-puma | before 4.3.12-150000.3.12.1 | 4.3.12-150000.3.12.1 |
| SUSE:Linux Enterprise High Availability Extension 15 SP3 | rubygem-puma | before 5.6.9-150000.3.18.1 | 5.6.9-150000.3.18.1 |
| SUSE:Linux Enterprise High Availability Extension 15 SP6 | rubygem-puma | before 5.6.9-150600.18.3.1 | 5.6.9-150600.18.3.1 |
| SUSE:Linux Enterprise High Availability Extension 15 SP6 | rubygem-puma | before 5.6.9-150600.18.3.1 | 5.6.9-150600.18.3.1 |
Same product
puma: all recordsOther highest-scoring records for the same primary product.
- CVE-2022-24790HTTP Request Smuggling in puma31Monitor
- CVE-2020-11077HTTP Smuggling via Transfer-Encoding Header in Puma31Monitor
- CVE-2020-11076HTTP Smuggling via Transfer-Encoding Header in Puma31Monitor
- CVE-2020-5247HTTP Response Splitting in Puma31Monitor
- CVE-2019-16770Potential DOS attack in Puma31Monitor
- CVE-2026-47737Puma PROXY Protocol v1 Accepts Repeated Protocol Headers on Persistent Connections30Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| debian:puma | 5.6.5-3+deb12u1 · Debian:12 | Package registry (OSV) |
| opensuse:rubygem-puma | 4.3.12-150000.3.12.1 · openSUSE:Leap 15.4 | Package registry (OSV) |
| red hat:candlepin | 0:4.3.11-1.el8sat · Red Hat:satellite:6.14::el8 | Package registry (OSV) |
| red hat:candlepin-selinux | 0:4.3.11-1.el8sat · Red Hat:satellite:6.14::el8 | Package registry (OSV) |
| red hat:mosquitto | 0:2.0.17-1.el8sat · Red Hat:satellite_capsule:6.14::el8 | Package registry (OSV) |
| red hat:mosquitto-debuginfo | 0:2.0.17-1.el8sat · Red Hat:satellite_capsule:6.14::el8 | Package registry (OSV) |
| red hat:mosquitto-debugsource | 0:2.0.17-1.el8sat · Red Hat:satellite_capsule:6.14::el8 | Package registry (OSV) |
| red hat:puppet-agent | 0:7.27.0-1.el8sat · Red Hat:satellite_capsule:6.14::el8 | Package registry (OSV) |
| red hat:puppetserver | 0:7.14.0-1.el8sat · Red Hat:satellite_capsule:6.14::el8 | Package registry (OSV) |
| red hat:rubygem-grpc | 0:1.58.0-1.el8sat · Red Hat:satellite:6.14::el8 | Package registry (OSV) |
| red hat:rubygem-puma | 0:6.3.1-1.el8sat · Red Hat:satellite:6.14::el8 | Package registry (OSV) |
| red hat:rubygem-puma-debuginfo | 0:6.3.1-1.el8sat · Red Hat:satellite:6.14::el8 | Package registry (OSV) |
| red hat:rubygem-puma-debugsource | 0:6.3.1-1.el8sat · Red Hat:satellite:6.14::el8 | Package registry (OSV) |
| red hat:rubygem-sidekiq | 0:6.5.12-1.el8sat · Red Hat:satellite:6.14::el8 | Package registry (OSV) |
| RubyGems:puma | 5.6.7 | Package registry (OSV) |
| RubyGems:puma | 6.3.1 | Package registry (OSV) |
| suse:rubygem-puma | 4.3.12-150000.3.12.1 · SUSE:Linux Enterprise High Availability Extension 15 SP1 | Package registry (OSV) |
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- No account or password is required.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- high · data can be read
- Integrity
- high · data or configuration can be modified
- Availability
- high · the service can be disrupted
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- High
- Integrity impact
- High
- Availability impact
- High
Weakness class (CWE)
CWE-444 · Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
nvd-primary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Attack patterns (CAPEC)
ATT&CK techniques
—
Change log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
- github.com/puma/puma/commit/690155e7d644b80eeef0a6094f9826ee41f1080a
- github.com/puma/puma/security/advisories/GHSA-68xg-gqqm-vgj8
Vendor advisories and official records. Exploit/PoC links are deliberately left out.