216.73.217.22

CVE-2026-48714

· Published 16/06/2026 00:16 · Modified 16/06/2026 15:46 · Author: The MITRE Corporation

Labels: CVE-2026-48714 2026-06-15CVE-2026-48714CWE-1321[email protected]

Essential information

Published
16/06/2026 00:16
Modified
16/06/2026 15:46
Author
The MITRE Corporation
Creator
The MITRE Corporation
CVSS
9.1 CRITICAL (v3.1)
CISA KEV
No
CWE
CWE-1321
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H

CVSS metrics

Description

i18next-http-middleware is a middleware to be used with Node.js web frameworks like express or Fastify and also for Deno. In versions prior to 3.9.7, the missingKeyHandler blocked the literal request-body keys __proto__, constructor, and prototype (added in 3.9.3, see GHSA-5fgg-jcpf-8jjw), but did not reject dotted variants such as "__proto__.polluted". Downstream backends that split the missing-key string on a configured keySeparator (notably i18next-fs-backend ≤ 2.6.5) hand these keys to an unguarded setPath() walker that writes to Object.prototype. Applications that expose missingKeyHandler to untrusted input AND use i18next-fs-backend ≤ 2.6.5 are directly exploitable for remote prototype pollution. Other downstream backends that split the missing-key string the same way may be similarly affected. Depending on the host application, polluted prototype properties may cause crashes, corrupted translation behaviour, configuration poisoning, or bypasses of property-based security checks. This issue has been fixed in version 3.9.7. If developers cannot upgrade immediately, they should do the following: do not expose missingKeyHandler to untrusted users (mount it behind authentication, or remove the route), add a request-body filter ahead of the handler that rejects any top-level key containing __proto__, constructor, or prototype after splitting on their configured keySeparator, and disable missing-key persistence (saveMissing: false) when accepting writes from untrusted input.

NVD status

Status
Undergoing Analysis — CVE has been recently published to the CVE List and has been received by the NVD.
Source
[email protected]
NVD
View on NVD

Affected products (CPE)

ProductCPE
i18next / i18next-http-middleware cpe:2.3:a:i18next:i18next-http-middleware:<3.9.7:*:*:*:*:*:*:*
i18next / i18next-fs-backend cpe:2.3:a:i18next:i18next-fs-backend:<=2.6.5:*:*:*:*:*:*:*

References