i18next-http-backend has Path Traversal & URL Injection via Unsanitised lng/ns

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

6.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

EPSS

• CVE-2026-41691: 0.31% estimated exploitation activity in the next 30 days; percentile 24.33 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary Versions of i18next-http-backend 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. Affected call sites: - readAny — lib/index.js:64: interpolate(resolvedLoadPath, { lng: languages.join('+'), ns: namespaces.join('+') }) - create — lib/index.js:123 (pre-patch): interpolate(addPath, { lng, ns: namespace }) The helper interpolate (lib/utils.js) previously returned the raw value with no encoding. In contrast, addQueryString already correctly uses encodeURIComponent for each query-string param — only the URL-path substitution was unprotected. Impact An attacker who can influence the…

Published by the source

22 Apr 2026, 17:41 UTC

Last modified by the source

11 May 2026, 13:53 UTC

Source last checked

26 Oct 2026, 12:51 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-q89c-q3h5-w34g

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-q89c-q3h5-w34g

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# Patch Next advisory brief: CVE-2026-41691

Advisory: i18next-http-backend has Path Traversal & URL Injection via Unsanitised lng/ns
IDs: CVE-2026-41691, GHSA-q89c-q3h5-w34g
Record: https://patchnext.com/advisories/cve-2026-41691 (revision 2, source checked 26 Oct 2026, 12:51 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: i18next-http-backend 3.0.5. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm i18next-http-backend: affected < 3.0.5; fixed in 3.0.5

## Suggested inspection (read-only)
- `npm ls i18next-http-backend --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on i18next-http-backend.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-q89c-q3h5-w34g (OSV record GHSA-q89c-q3h5-w34g lists affected ranges: npm i18next-http-backend >=0 <3.0.5 (fixed))
- Verified: https://github.com/advisories/GHSA-q89c-q3h5-w34g (GitHub-reviewed advisory GHSA-q89c-q3h5-w34g lists affected ranges: npm i18next-http-backend >=0 <3.0.5)

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