Puma is a simple, fast, multi-threaded, parallel HTTP 1.1 server for Ruby/Rack applications. When using Puma behind a proxy that does not properly validate that the incoming HTTP request matches the RFC7230 standard, Puma and the frontend proxy may disagree on where a request starts and ends. This would allow requests to be smuggled via the front-end proxy to Puma. The vulnerability has been fixed in 5.6.4 and 4.3.12. Users are advised to upgrade as soon as possible. Workaround: when deploying a proxy in front of Puma, turning on any and all functionality to make sure that the request matches the RFC7230 standard.
CVSS Details
- CVSS 3.1 Base Score: 9.1
- CVSS 3.1 Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N)
Covered by Rapid7
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Arch Linux | arch-linux-upgrade-latest | Jul 11, 2025 | Mar 30, 2022 | |
| Debian | debian-upgrade-puma | Aug 29, 2022 | Mar 30, 2022 | |
| Gentoo Linux | gentoo-linux-upgrade-www-servers-puma | Aug 16, 2022 | Mar 30, 2022 | |
| Suse | — | suse-upgrade-ruby2-5-rubygem-pumasuse-upgrade-ruby2-5-rubygem-puma-doc | Oct 26, 2022 | Mar 30, 2022 |
| Ubuntu | ubuntu-pro-upgrade-puma | Mar 8, 2024 | Mar 30, 2022 |
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