CVE-2026-105800: i18next i18next-HTTP-Backend

Low severity, CVSS 3.7. EPSS: 0.3% chance of exploitation in the next 30 days.

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.

Affected products

• i18next i18next-HTTP-Backend: before 4.0.2 (fixed in 4.0.2)

Published 2026-10-06. Last modified 2026-10-06.