HTTP Response Splitting Affecting i18next-http-middleware package, versions <3.9.3
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-JS-I18NEXTHTTPMIDDLEWARE-16415527
- published4 May 2026
- disclosed22 Apr 2026
- creditUnknown
Introduced: 22 Apr 2026
NewCVE-2026-41683 (opens in a new tab)How to fix?
Upgrade i18next-http-middleware to version 3.9.3 or higher.
Overview
i18next-http-middleware is an i18next-http-middleware is a middleware to be used with Node.js web frameworks like express or Fastify and also for Deno.
Affected versions of this package are vulnerable to HTTP Response Splitting via the lng parameter, which is passed through to the response's Content-Language header, after some sanitization with utils.escape(). An attacker can inject arbitrary HTTP headers or cause denial of service by including carriage return and line feed (CRLF) characters. This can result in session fixation, cache poisoning, reflected content injection, or process-wide unhandled exceptions depending on the Node.js version.
Response splitting is possible on applications based on Node versions prior to 14.6.0, which may enable cross-site scripting. Newer versions of Node are susceptible to denial of service only, since the CRLF sequence triggers a ERR_INVALID_CHAR, which is unhandled.