Copyright © 2012 Red Hat, Inc. All rights reserved. Important 2026-07-14T19:45:16 puma: Puma: Source IP spoofing via PROXY protocol header re-parsing 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N CWE-358

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.

A flaw was found in Puma, a Ruby/Rack web server. When `set_remote_address proxy_protocol: :v1` is enabled and persistent connections are used, Puma incorrectly re-parses PROXY protocol headers after each keep-alive request on the same connection. This allows a remote attacker to inject a second PROXY header, leading to source IP (Internet Protocol) spoofing and potentially impacting security logging or access control decisions.

This flaw only affects Puma deployments that explicitly enable `set_remote_address proxy_protocol: :v1` together with persistent (keep-alive) connections to the proxy. This is not Puma default configuration. Upgrade puma to 7.2.1 or 8.0.2 (or later). If an immediate upgrade is not possible, remove the `set_remote_address proxy_protocol: :v1` configuration, or disable persistent connections (`enable_keep_alives false`), to prevent PROXY protocol v1 header re-parsing on the same connection. Red Hat 3scale API Management Platform 2 Not affected 3scale-amp21/backend Red Hat 3scale API Management Platform 2 Not affected 3scale-amp21/zync Red Hat 3scale API Management Platform 2 Not affected 3scale-amp22/backend Red Hat 3scale API Management Platform 2 Not affected 3scale-amp22/zync Red Hat 3scale API Management Platform 2 Not affected 3scale-amp2/backend-rhel8 Red Hat 3scale API Management Platform 2 Not affected 3scale-amp2/zync-rhel8 Red Hat 3scale API Management Platform 2 Not affected 3scale-amp2/zync-rhel9 Red Hat Enterprise Linux 10 Not affected pcs Red Hat Enterprise Linux 8 Not affected pcs Red Hat Enterprise Linux 9 Not affected pcs Red Hat Satellite 6 Not affected rubygem-puma Red Hat Satellite 6 Not affected satellite:el8/rubygem-puma https://www.cve.org/CVERecord?id=CVE-2026-47737 https://nvd.nist.gov/vuln/detail/CVE-2026-47737 https://github.com/puma/puma/commit/439c6136d9c2275721b7864db3ee78af7c80889f https://github.com/puma/puma/commit/ebe9db3929ab8299d19c8f5b41e8ef4f4b22fa58 https://github.com/puma/puma/pull/3944 https://github.com/puma/puma/pull/3947 https://github.com/puma/puma/releases/tag/v7.2.1 https://github.com/puma/puma/releases/tag/v8.0.2 https://github.com/puma/puma/security/advisories/GHSA-2vqw-3mp8-cgmx