Puma is a Ruby/Rack web server built for parallelism. From 5.5.0 until 7.2.1 and 8.0.2, Puma is vulnerable to source IP spoofing when set_remote_address proxy_protocol: :v1 is enabled and persistent connections are used because Puma incorrectly re-parses PROXY protocol headers after each keep-alive request on the same connection, allowing an attacker to inject a second PROXY header and overwrite REMOTE_ADDR. This issue is fixed in versions 7.2.1 and 8.0.2.
CVE-2026-47737
HIGHPre-NVD 7.57.5—
EchelonGraph scoreMEDIUM confidence
This high-severity CVE scores 7.5 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.2%, top 93% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).
Triggered by: NVD CVSS baseline
Sources: epss, secondary
7.5
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
- High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 0%CVSS: 7.5Exploit: NoneExposed: 0
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 7.5
- EG Score
- 7.5(medium)
- EG Risk
- —
- EPSS
- 7.5%
- KEV
- Not listed
Published
June 9, 2026
Last Modified
July 15, 2026
Advisory Details (7)
Auto-updated Jul 15, 2026Patch available. Sources: github_release, github, github_commit, github_pr.
github Patch Available
Puma PROXY Protocol v1 Accepts Repeated Protocol Headers on Persistent Connections · Advisory · puma/puma · GitHub
https://github.com/puma/puma/security/advisories/GHSA-2vqw-3mp8-cgmxgithub_release Patch Available
v8.0.2
Patch available: puma/puma v8.0.2
https://github.com/puma/puma/releases/tag/v8.0.2github_release Patch Available
v7.2.1
Patch available: puma/puma v7.2.1
https://github.com/puma/puma/releases/tag/v7.2.1github_pr Patch Available
7.2.1 backport
Patch available: puma/puma v7.2.1 (PR #3947 merged 2026-05-26)
https://github.com/puma/puma/pull/3947github_pr Patch Available
8.0.2 backport
Patch available: puma/puma v8.0.2 (PR #3944 merged 2026-05-26)
https://github.com/puma/puma/pull/3944github_commit Patch Available
commit ebe9db3929ab (puma/puma)
Patch available: puma/puma v7.2.1 (contains commit ebe9db3929ab)
https://github.com/puma/puma/commit/ebe9db3929ab8299d19c8f5b41e8ef4f4b22fa58github_commit Patch Available
commit 439c6136d9c2 (puma/puma)
Patch available: puma/puma v8.0.2 (contains commit 439c6136d9c2)
https://github.com/puma/puma/commit/439c6136d9c2275721b7864db3ee78af7c80889fVendor Advisories for CVE-2026-47737(1)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
Affected Packages
(1 across 1 ecosystem)
RubyGems(1)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| puma | 5.5.0 ... 7.2.0 (37 versions) | 7.2.1 | — |
Weakness Classification(2)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 7× in last 7d / 8× in last 30d)
Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.
- 2026-07-22 14:08 UTCEPSS rescore
- 2026-07-21 15:24 UTCEPSS rescore
- 2026-07-20 17:08 UTCEPSS rescore
- 2026-07-19 14:31 UTCEPSS rescore
- 2026-07-19 02:29 UTCEPSS rescore
- 2026-07-18 10:04 UTCEPSS rescore
- 2026-07-16 17:03 UTCEPSS rescore
- 2026-07-15 16:57 UTCEPSS rescore
- 2026-06-14 23:18 UTCEPSS rescore
- 2026-06-13 23:00 UTCEPSS rescore
- 2026-06-12 23:12 UTCEPSS rescore
- 2026-06-09 01:01 UTCEG score recompute
Frequently asked(5)
What is CVE-2026-47737?
CVE-2026-47737 is a high vulnerability published on June 9, 2026. Puma is a Ruby/Rack web server built for parallelism. From 5.5.0 until 7.2.1 and 8.0.2, Puma is vulnerable to source IP spoofing when setremoteaddress proxyprotocol: :v1 is enabled and persistent connections are used because Puma incorrectly re-parses PROXY protocol headers after each keep-alive…
When was CVE-2026-47737 disclosed?
CVE-2026-47737 was first published in the National Vulnerability Database on June 9, 2026, with the most recent update on July 15, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-47737 actively exploited?
CVE-2026-47737 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 7.5% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-47737?
CVE-2026-47737 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2026-47737?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-47737, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.
Dependency Blast Radius
See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-47737
Is Your Infrastructure Affected by CVE-2026-47737?
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