# CVE-2026-47737: puma: Puma is a Ruby/Rack web server built for parallelism

CVE-2026-47737 is fixed in puma on 1 platform, first by DEBIAN-CVE-2026-47737, released July 18, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-47737
- Priority: High
- CVSS: 7.5 (high)
- EPSS: 0.0018
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Jul 14, 2026

## 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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | puma Debian 12.15 (bookworm) | 5.6.5-3+deb12u2 | [DEBIAN-CVE-2026-47737](https://patchblox.com/security/data/fix/linux/debian-cve-2026-47737.md) | Jul 18, 2026 |
| Linux | puma Debian 14 | 8.0.2-1 | [DEBIAN-CVE-2026-47737](https://patchblox.com/security/data/fix/linux/debian-cve-2026-47737.md) | Jul 18, 2026 |

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Data as of 2026-11-08T06:59:42Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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