Vulnerability in Puma
CVE-2026-47737
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N.
EPSS exploit prediction
EPSS: 0.002 (6.9th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 7th percentile — 6.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.002 · change: -0.001
Affected products
- Puma — versions >= 5.5.0, < 7.2.1, >= 8.0.0, < 8.0.2
Weakness classification (CWE)
References
- github.com/puma/puma/security/advisories/GHSA-2vqw-3mp8-cgmx
- github.com/puma/puma/pull/3944
- github.com/puma/puma/pull/3947
- github.com/puma/puma/commit/439c6136d9c2275721b7864db3ee78af7c80889f
- github.com/puma/puma/commit/ebe9db3929ab8299d19c8f5b41e8ef4f4b22fa58
- github.com/puma/puma/releases/tag/v7.2.1
- github.com/puma/puma/releases/tag/v8.0.2
Frequently asked questions
- What is CVE-2026-47737?
- CVE-2026-47737 is a high-severity vulnerability in Puma, classified under Authentication Bypass by Spoofing. CVSS score: 7.5/10. Published 2026-07-14.
- How severe is CVE-2026-47737?
- High severity. CVSS v3 base score is 7.5 out of 10.