High [CVE-2026-47737] Source IP spoofing via PROXY protocol header re-parsing
This high-severity Red Hat Linux advisory covers CVE-2026-47737.
Aggregated and source-linked by VulniPulse. Data sources, validation and limitations.
VulniPulse record published Record updated
Summary
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. 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 is not Puma default configuration. Red Hat severity: Important — CVSS 7.5 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N).
Weakness: CWE-358. Red Hat lists Red Hat 3scale API Management Platform 2; Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 8; Red Hat Enterprise Linux 9; Red Hat Satellite 6 as not affected.
Is CVE-2026-47737 exploited?
No exploitation is reported in the sources VulniPulse tracks: CVE-2026-47737 is not in the CISA KEV catalog (checked ) and this advisory does not report exploitation. That is not proof the vulnerability cannot be exploited.
How do I fix CVE-2026-47737?
Upgrade to a fixed release named by Red Hat:
- 7.2.1
- 8.0.2
Confirm against the vendor advisory before you patch.
- 5.5.0
Official advisory · high-confidence parse· fetched 6 days ago·verify at source
- 7.2.1
- 8.0.2
Official advisory · high-confidence parse· fetched 6 days ago·verify at source
Mitigation checklist
- 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.
Official advisory · high-confidence parse· fetched 6 days ago·verify at source
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