i18next-locize-backend has URL Injection via Unsanitized Path Parameters

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

6.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

EPSS

• CVE-2026-41885: 0.22% estimated exploitation activity in the next 30 days; percentile 13.06 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary Versions of i18next-locize-backend prior to 9.0.2 interpolate lng, ns, projectId, and version directly into the configured loadPath / privatePath / addPath / updatePath / getLanguagesPath URL templates with no path-component validation and no encoding. When an application exposes any of these values to user-controlled input (?lng= / ?ns= query parameters via i18next-browser-languagedetector, cookies, request headers, or a URL-derived projectId), a crafted value can change the structure of the outgoing request URL. Affected call sites in lib/index.js (pre-patch): the interpolate() helper is used at the five URL-build sites — readAny/read (line 415 for private, 426 for public), getLanguages (lines 271 and 296), and writePage (lines 616 and 622) for the missing-key and update POST paths. The helper interpolate in lib/utils.js substitutes raw values with no encoding. Impact An attacker who can influence lng, ns, projectId, or version can: - Path traversal — lng = '../../admin'…

Published by the source

22 Apr 2026, 20:28 UTC

Last modified by the source

13 May 2026, 13:52 UTC

Source last checked

26 Oct 2026, 12:52 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-mgcp-mfp8-3q45

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-mgcp-mfp8-3q45

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# Patch Next advisory brief: CVE-2026-41885

Advisory: i18next-locize-backend has URL Injection via Unsanitized Path Parameters
IDs: CVE-2026-41885, GHSA-mgcp-mfp8-3q45
Record: https://patchnext.com/advisories/cve-2026-41885 (revision 2, source checked 26 Oct 2026, 12:52 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: i18next-locize-backend 9.0.2. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm i18next-locize-backend: affected < 9.0.2; fixed in 9.0.2

## Suggested inspection (read-only)
- `npm ls i18next-locize-backend --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on i18next-locize-backend.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-mgcp-mfp8-3q45 (OSV record GHSA-mgcp-mfp8-3q45 lists affected ranges: npm i18next-locize-backend >=0 <9.0.2 (fixed))
- Verified: https://github.com/advisories/GHSA-mgcp-mfp8-3q45 (GitHub-reviewed advisory GHSA-mgcp-mfp8-3q45 lists affected ranges: npm i18next-locize-backend >=0 <9.0.2)

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