# CVE-2026-105800: i18next-http-backend incomplete URL validation permits SSRF

Source: https://junglewise.ai/threats/cve-2026-105800-i18next-http-backend-is-a-backend-layer-for-i18next-that-loads  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-06  
License: CC BY 4.0 with a link back

CVE-2026-105800 · Severity: low · CVSS 3.7 · Published 2026-10-06

i18next-http-backend is a backend layer for i18next that loads translation resources in Node.js, browsers, and Deno. Prior to 4.0.2, attacker-controlled language or namespace values interpolated into a custom loadPath or addPath that begins directly with {{lng}} or {{ns}} can make colon-based input become an absolute URL or, in browsers, make a double-slash namespace become a protocol-relative URL. The resulting request can leave the intended origin and cause URL injection or server-side request forgery. The default /locales/{{lng}}/{{ns}}.json template and templates with a leading path or origin are not affected because the placeholder does not occupy the URL's structural beginning. This issue is fixed in version 4.0.2.

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-2026-105800 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-105800 being exploited in the wild.

**How severe is CVE-2026-105800?** Low severity, with a CVSS score of 3.7, published 6 October 2026.

**Which products and versions are affected?** i18next-http-backend (npm) < 4.0.2, SEMVER:introduced=0,fixed=4.0.2.

**Is there a fix for CVE-2026-105800?** Yes. i18next-http-backend (npm): upgrade to 4.0.2 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**Am I affected by CVE-2026-105800?** 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 4.0.2 or later

  ```sh
  npm install i18next-http-backend@4.0.2
  ```


## Affected products

- i18next-http-backend (npm) < 4.0.2, SEMVER:introduced=0,fixed=4.0.2

## Identifiers

- CVE-2026-105800
- GHSA-xvq9-wjp8-hwqf

## 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 URL injection and path traversal](https://junglewise.ai/threats/cve-2026-41691-i18next-http-backend-url-injection-and-path-traversal)