{"id":"CVE-2024-45614","aliases":["GHSA-9hf4-67fc-4vf4"],"url":"https://o3.security/vulnerability/CVE-2024-45614","summary":"Header normalization allows for client to clobber proxy set headers in Puma","details":"Puma is a Ruby/Rack web server built for parallelism. In affected versions clients could clobber values set by intermediate proxies (such as X-Forwarded-For) by providing a underscore version of the same header (X-Forwarded_For). Any users relying on proxy set variables is affected. v6.4.3/v5.6.9 now discards any headers using underscores if the non-underscore version also exists. Effectively, allowing the proxy defined headers to always win. Users are advised to upgrade. Nginx has a underscores_in_headers configuration variable to discard these headers at the proxy level as a mitigation. Any users that are implicitly trusting the proxy defined headers for security should immediately cease doing so until upgraded to the fixed versions.","published":"2024-09-19T22:42:33.974Z","modified":"2026-08-12T15:16:03.908794Z","cvss":{"score":5.4,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:N"},"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"RubyGems","name":"puma","fixedVersion":"5.6.9"},{"ecosystem":"RubyGems","name":"puma","fixedVersion":"6.4.3"}],"fix":null,"references":[{"type":"WEB","url":"https://lists.debian.org/debian-lts-announce/2024/11/msg00004.html"},{"type":"WEB","url":"https://nginx.org/en/docs/http/ngx_http_core_module.html#underscores_in_headers"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/45xxx/CVE-2024-45614.json"},{"type":"ADVISORY","url":"https://github.com/puma/puma/security/advisories/GHSA-9hf4-67fc-4vf4"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2024-45614"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T15:16:03.908794Z"}}