# CVE-2026-118258: i18next-http-backend: Query-parameter injection through & and = in lng when loadPath/addPath puts {{lng}} in the query string

Status: published. Published: 2026-10-28. Updated: 2026-11-03.

i18next-http-backend is a backend layer for i18next that loads translation resources in Node.js, browsers, and Deno. Prior to 4.0.4, interpolateUrl inserts unencoded language and namespace values into loadPath or addPath templates without rejecting ampersand (&), equals (=), or semicolon (;) query separators. When a template places lng or ns in the query string and an attacker controls that value, the attacker can add or override parameters on browser or server-side translation requests, potentially exposing other namespaces or tenants or changing backend behavior through the application's network position and credentials. This vulnerability is the result of an incomplete fix for CVE-2026-41691. This issue is fixed in version 4.0.4.

## Remediation

- fix: i18next-http-backend (npm): OSV reports a fixed version 4.0.4. Check the advisory for supported release branches. (source: OSV GHSA-3cmx-xjww-583x) — https://github.com/advisories/GHSA-3cmx-xjww-583x

## Affected products and versions

- i18next / i18next-http-backend: < 4.0.4 (affected). Source: CNA: GitHub_M
-  / i18next-http-backend (i18next-http-backend): ≥ 0; < 4.0.4 (affected, semver); OSV events: introduced 0; fixed 4.0.4. Source: OSV GHSA-3cmx-xjww-583x

## Severity and prioritization

- CVSS 3.1: 3.7 (low); CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N; source: CNA: GitHub_M

- CISA KEV: No listing in collected sources

- EPSS: 0.28% as of 2026-11-02; percentile 20.56%

- SSVC: exploitation poc; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-74

## Exploit evidence

- exploit: https://github.com/i18next/i18next-http-backend/security/advisories/GHSA-3cmx-xjww-583x (ADP: CISA-ADP)

## References

- https://github.com/i18next/i18next-http-backend/security/advisories/GHSA-3cmx-xjww-583x (CNA: GitHub_M; x_refsource_CONFIRM)

- https://github.com/i18next/i18next-http-backend/commit/b0eef9efd425055c554787cef7f878de33bbf510 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/i18next/i18next-http-backend/releases/tag/v4.0.4 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/i18next/i18next-http-backend/security/advisories/GHSA-3cmx-xjww-583x (ADP: CISA-ADP; exploit)

- https://github.com/advisories/GHSA-3cmx-xjww-583x (OSV / GitHub Security Advisories; advisory)

- https://osv.dev/vulnerability/GHSA-3cmx-xjww-583x (OSV / GitHub Security Advisories; osv)

## Provenance

- CNA: GitHub_M: https://www.cve.org/CVERecord?id=CVE-2026-118258; retrieved 2026-11-03; source updated 2026-11-03

- OSV / GitHub Security Advisories: https://osv.dev/vulnerability/GHSA-3cmx-xjww-583x; retrieved 2026-11-03; source updated 2026-10-28

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-118258; retrieved 2026-11-03; source updated Not reported

Revision: 3d335aa9a4f60bbb60b551fd2759115913e8a78c898ca91c8c69ee5730074d92

Canonical: https://y2.dev/cve/CVE-2026-118258

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