# CVE-2026-41691: i18next-http-backend URL injection and path traversal

Source: https://junglewise.ai/threats/cve-2026-41691-i18next-http-backend-url-injection-and-path-traversal  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-05-07. Updated: 2026-05-29  
License: CC BY 4.0 with a link back

CVE-2026-41691 · Severity: medium · CVSS 6.5 · Published 2026-05-07

i18next-http-backend is a JavaScript library used to load translation files for website internationalization. A vulnerability in how the library handles language and namespace settings allows an attacker to manipulate the web requests made by the application. This could lead to unauthorized access to internal files, bypasses of security filters, or the redirection of requests to unintended locations, potentially exposing sensitive configuration data.

Technologies: [i18next-http-backend (npm)](https://junglewise.ai/threats/technologies/i18next-http-backend). Vendors: [npm](https://junglewise.ai/threats/vendors/npm).

## Quick answers

**Is CVE-2026-41691 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-41691 being exploited in the wild.

**How severe is CVE-2026-41691?** Medium severity, with a CVSS score of 6.5, published 7 May 2026.

**Which products and versions are affected?** i18next-http-backend (npm) < 3.0.5, SEMVER:introduced=0,fixed=3.0.5.

**Is there a fix for CVE-2026-41691?** Yes. i18next-http-backend (npm): upgrade to 3.0.5 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-41691 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-41691?** Check whether you run i18next-http-backend (npm) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- i18next-http-backend (npm): upgrade to 3.0.5 or later

  ```sh
  npm install i18next-http-backend@3.0.5
  ```


## Technical details

i18next-http-backend versions prior to 3.0.5 are vulnerable to URL injection (CWE-74) and path traversal (CWE-22). The library's 'interpolate' function in 'lib/utils.js' fails to encode or validate 'lng' (language) and 'ns' (namespace) values before substituting them into 'loadPath' or 'addPath' templates. Because these values are often sourced from user-controlled inputs like query parameters or headers via 'i18next-browser-languagedetector', a remote attacker can inject special characters (e.g., '../', '?', '#'). This allows for path traversal to access arbitrary files in Server-Side Rendering (SSR) environments using the 'file://' scheme, or query-string injection to bypass authorization logic. The issue is fixed in version 3.0.5 by implementing a new 'interpolateUrl' function that validates URL segments against a blocklist of special characters and length limits.

## Affected products

- i18next i18next-http-backend < 3.0.5

## Identifiers

- CVE-2026-41691
- GHSA-q89c-q3h5-w34g

## Timeline

- 2026-04-18: patched: Fix committed in version 3.0.5
- 2026-04-18: advisory: GitHub Security Advisory GHSA-q89c-q3h5-w34g published
- 2026-05-07: disclosed: CVE-2026-41691 published to NVD

## References

- [https://github.com/i18next/i18next-http-backend/commit/4cee84f229c637b9c182366d3156f726d407a621](https://github.com/i18next/i18next-http-backend/commit/4cee84f229c637b9c182366d3156f726d407a621)
- [https://github.com/i18next/i18next-http-backend/security/advisories/GHSA-q89c-q3h5-w34g](https://github.com/i18next/i18next-http-backend/security/advisories/GHSA-q89c-q3h5-w34g)

## Related threats

- [i18next-http-backend: Query-parameter injection through & and = in lng when loadPath/addPath puts {{lng}} in the query string](https://junglewise.ai/threats/cve-2026-118258-i18next-http-backend-is-a-backend-layer-for-i18next-that-loads)
- [Duplicate Advisory: Namespace value starting with / forms a protocol-relative URL when loadPath/addPath places {{ns}} right after a / (bypass of the // check added for GHSA-xvq9-wjp8-hwqf)](https://junglewise.ai/threats/duplicate-advisory-namespace-value-starting-with-forms-a-protocol-0773444c)
- [i18next-http-backend: Namespace value starting with / forms a protocol-relative URL when loadPath/addPath places {{ns}} right after a / (bypass of the // check added for GHSA-xvq9-wjp8-hwqf)](https://junglewise.ai/threats/cve-2026-115730-i18next-http-backend-4-0-2-contains-an-incomplete-fix-in)
- [i18next-http-backend incomplete URL validation permits SSRF](https://junglewise.ai/threats/cve-2026-105800-i18next-http-backend-is-a-backend-layer-for-i18next-that-loads)