i18next i18next-http-middleware up to 3.9.2 path traversal

Summaryinfo

A vulnerability was found in i18next i18next-http-middleware up to 3.9.2 and classified as critical. Affected by this vulnerability is an unknown functionality. Executing a manipulation can lead to path traversal. This vulnerability is handled as CVE-2026-41690. The attack can be executed remotely. There is not any exploit available. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability classified as critical was found in i18next i18next-http-middleware up to 3.9.2. This vulnerability affects an unknown code. The manipulation with an unknown input leads to a path traversal vulnerability. The CWE definition for the vulnerability is CWE-22. The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

18next-http-middleware is a middleware to be used with Node.js web frameworks like express or Fastify and also for Deno. Versions prior to 3.9.3 allow an unauthenticated HTTP client to pollute Object.prototype in the Node.js process hosting the middleware, via two unvalidated entry points that reach internal object-key writes: getResourcesHandler and missingKeyHandler. This can break authorisation checks (if (user.isAdmin) returning true for any user), cause type-confusion DoS, and depending on downstream code it can be chained into RCE.

The advisory is shared for download at github.com. This vulnerability was named CVE-2026-41690 since 04/22/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. There are neither technical details nor an exploit publicly available. The MITRE ATT&CK project declares the attack technique as T1006.

Upgrading to version 3.9.3 eliminates this vulnerability.

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Productinfo

Type

• Middleware

Vendor

• i18next

Name

• i18next-http-middleware

Version

• 3.9.0
• 3.9.1
• 3.9.2

Website

• Product: https://github.com/i18next/i18next-http-middleware/

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