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

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). 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
    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

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