{"cve":"CVE-2023-40175","nvd":{"published":"2023-08-18T22:15:11.653","modified":"2026-06-17T06:16:33.543","status":"Modified","description":"Puma is a Ruby/Rack web server built for parallelism. Prior to versions 6.3.1 and 5.6.7, puma exhibited incorrect behavior when parsing chunked transfer encoding bodies and zero-length Content-Length headers in a way that allowed HTTP request smuggling. Severity of this issue is highly dependent on the nature of the web site using puma is. This could be caused by either incorrect parsing of trailing fields in chunked transfer encoding bodies or by parsing of blank/zero-length Content-Length headers. Both issues have been addressed and this vulnerability has been fixed in versions 6.3.1 and 5.6.7. Users are advised to upgrade. There are no known workarounds for this vulnerability.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","score":9.8},"cwes":["CWE-444"],"references":["https://github.com/puma/puma/commit/690155e7d644b80eeef0a6094f9826ee41f1080a","https://github.com/puma/puma/security/advisories/GHSA-68xg-gqqm-vgj8","https://github.com/puma/puma/commit/690155e7d644b80eeef0a6094f9826ee41f1080a","https://github.com/puma/puma/security/advisories/GHSA-68xg-gqqm-vgj8"],"products":["puma:puma"],"source":"nvd","synced_at":"2026-10-19T21:39:14.809778102+00:00"},"epss":{"cve":"CVE-2023-40175","score":0.00847,"percentile":0.58076,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-68xg-gqqm-vgj8","url":"https://osv.dev/vulnerability/GHSA-68xg-gqqm-vgj8","summary":"Puma HTTP Request/Response Smuggling vulnerability","modified":"2026-09-10T03:49:57.566567193Z","packages":[{"ecosystem":"RubyGems","name":"puma","purl":"pkg:gem/puma","ranges":["<5.6.7"],"fixed":["5.6.7"]},{"ecosystem":"RubyGems","name":"puma","purl":"pkg:gem/puma","ranges":[">=6.0.0 <6.3.1"],"fixed":["6.3.1"]}]}],"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."]}