{"cve":"CVE-2024-45614","nvd":{"published":"2024-09-19T23:15:11.703","modified":"2026-06-17T07:54:34.120","status":"Modified","description":"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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:N","score":5.4},"cwes":["CWE-444","CWE-639"],"references":["https://github.com/puma/puma/security/advisories/GHSA-9hf4-67fc-4vf4","https://nginx.org/en/docs/http/ngx_http_core_module.html#underscores_in_headers","https://lists.debian.org/debian-lts-announce/2024/11/msg00004.html"],"products":["puma:puma"],"source":"nvd","synced_at":"2026-10-19T21:54:38.012257375+00:00"},"epss":{"cve":"CVE-2024-45614","score":0.0064,"percentile":0.50674,"date":"2026-11-01"},"kev":null,"osv":[{"id":"GHSA-9hf4-67fc-4vf4","url":"https://osv.dev/vulnerability/GHSA-9hf4-67fc-4vf4","summary":"Puma's header normalization allows for client to clobber proxy set headers","modified":"2026-09-10T03:50:56.027397803Z","packages":[{"ecosystem":"RubyGems","name":"puma","purl":"pkg:gem/puma","ranges":["<5.6.9"],"fixed":["5.6.9"]},{"ecosystem":"RubyGems","name":"puma","purl":"pkg:gem/puma","ranges":[">=6.0.0 <6.4.3"],"fixed":["6.4.3"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}