CVE-2026-41683 Details
Description
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.
A vulnerability in i18next-http-middleware versions prior to 3.9.3 allows user-controlled language values to be written into the Content-Language response header. These values are first processed by an HTML-entity encoder that fails to remove control characters. In applications using an older version of i18next (prior to 19.5.0) that still applied backward-compatibility fallbacks, CRLF sequences in the lng parameter could be injected into the response header verbatim. This vulnerability can lead to HTTP response splitting and denial-of-service, depending on the Node.js version.
Users are advised to upgrade to i18next-http-middleware version 3.9.3 or later. For those unable to upgrade, a partial mitigation involves front-proxying the middleware with a WAF rule that rejects control characters in query parameters, cookies, and path segments.
Metrics
CVSS 4.0 Severity and Vector Strings:
VolerionCVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
Volerion
Assessed May 8, 2026CISA-ADP
Assessed May 8, 2026References to Advisories, Solutions, and Tools
By selecting these links, you will be leaving this site. These are references gathered from the official CVE record and are not endorsed by Volerion.
| URL | Source(s) | Tag(s) |
|---|---|---|
| https://github.com/i18next/i18next-http-middleware/security/advisories/GHSA-c3h8-g69v-pjrg | [email protected] | AdvisoryRemedyVendor |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-113 | Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Request/Response Splitting') | [email protected] |
| CWE-79 | Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| i18next-http-middleware | All versions |
CPE
Remediation
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Change History
3 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jun 17, 2026 | CVE Modified | [email protected] |
| Jun 17, 2026 | CVE Modified | CISA-ADP |
| May 8, 2026 | New CVE Received | [email protected] |