CVE-2026-41691 i18next-http-backend has Path Traversal & URL Injection via Unsanitised lng/ns
Attackers can inject path traversal or URL structures via unsanitized language/namespace inputs, potentially accessing unauthorized resources or bypassing security controls.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-41691?
CVE-2026-41691 is a medium-severity path traversal vulnerability in i18next-http-backend, published on 7 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Copilot said: i18nextify is a JavaScript library that adds i18nextify is a JavaScript library that adds website internationalization via a script tag, without source code changes. Versions prior to 3.0.5 interpolate the lng and ns values directly into the configured loadPath / addPath URL template without any encoding, validation, or path sanitisation. When an application exposes the language-code selection to user-controlled input (the default — i18next-browser-languagedetector reads ?lng= query params, cookies, localStorage, and request headers), an attacker can inject characters that change the structure of the outgoing request URL. This is a single URL-injection vulnerability. The attacker-controlled value is neutralised before it is used as part of an output URL string; the attack shape covers both path traversal and broader URL-structure injection — both are closed by the one interpolateUrl sanitisation fix. This issue has been fixed in version 3.0.5. If users cannot upgrade immediately, they can work around the issue by sanitising lng / ns before they reach i18next (strip .., /, \, ?, #, %, whitespace, and control characters; cap the length).
Which versions are affected by CVE-2026-41691?
2 open source packages ship an affected version, including i18next-http-backend. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
i18next-http-backend npm | All versions | 3.0.5 |
i18next-http-backend npm | All versions | 3.0.5 |
Products include I18next I18next-Http-Backend.
How do I fix CVE-2026-41691?
Upgrade i18next-http-backend to 3.0.5 or later.
Upgrade, and resolve every user-supplied path against an allowed base folder before opening it. More about Path traversal.
Is CVE-2026-41691 being exploited?
There is no known exploitation of CVE-2026-41691 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-41691, GHSA-q89c-q3h5-w34g.