Description
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.
References7
- github.com/puma/puma/commit/439c6136d9c2275721b7864db3ee78af7c8…
- github.com/puma/puma/commit/ebe9db3929ab8299d19c8f5b41e8ef4f4b2…
- github.com/puma/puma/pull/3944
- github.com/puma/puma/pull/3947
- github.com/puma/puma/releases/tag/v7.2.1
- github.com/puma/puma/releases/tag/v8.0.2
- github.com/puma/puma/security/advisories/GHSA-2vqw-3mp8-cgmx
Metrics
- CVSS 3.1
-
7.5
HIGH
Score source: CNA
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N - EPSS — exploit probability
- 0% percentile: 7 · as of 15 November 2026
- CWE
- CWE-290CWE-345
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.