CVE-2026-41683
i18next-http-middleware is a middleware to be used with Node.js web frameworks like express or Fastify and also for Deno.
Impact
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.
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| npm | i18next-http-middleware | < 3.9.3 | 3.9.3 |
Weakness classification
References
- NVD record
- CVE.org record
- GitHub advisory
- https://github.com/advisories/GHSA-c3h8-g69v-pjrg
- https://github.com/i18next/i18next-http-middleware/security/advisories/GHSA-c3h8-g69v-pjrg
- https://github.com/i18next/i18next-http-middleware/commit/65301c194593d46a84623b64e5fde2f51d3550f6
- https://nvd.nist.gov/vuln/detail/CVE-2026-41683