{"id":"CVE-2026-41683","aliases":["GHSA-c3h8-g69v-pjrg"],"url":"https://o3.security/vulnerability/CVE-2026-41683","summary":"HTTP response splitting and DoS in i18next-http-middleware via unsanitised Content-Language header","details":"i18next-http-middleware is a middleware to be used with Node.js web frameworks like express or Fastify and also for Deno. Prior to version 3.9.3, i18next-http-middleware wrote user-controlled language values into the Content-Language response header after passing them through utils.escape(), which is an HTML-entity encoder that does not strip carriage return, line feed, or other control characters. When the application used an older i18next (< 19.5.0) that still exercised the backward-compatibility fallback at LanguageDetector.js:100 or otherwise produced a raw detected value, CRLF sequences in the attacker-controlled lng parameter reached res.setHeader('Content-Language', ...) verbatim. This issue has been patched in version 3.9.3.","published":"2026-05-08T15:27:05.036Z","modified":"2026-08-07T11:31:12.401507450Z","cvss":{"score":8.6,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:L"},"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"npm","name":"i18next-http-middleware","fixedVersion":"3.9.3"}],"fix":null,"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/41xxx/CVE-2026-41683.json"},{"type":"ADVISORY","url":"https://github.com/i18next/i18next-http-middleware/security/advisories/GHSA-c3h8-g69v-pjrg"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-41683"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-07T11:31:12.401507450Z"}}