Prototype Pollution in I18next I18next-http-middleware
CVE-2026-48714
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 p…
Vulnerability class: Prototype Pollution
CVSS v3 metric
CVSS v3 base score 9.1 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H.
Affected products
- I18next I18next-http-middleware — versions < 3.9.7
Weakness classification (CWE)
References
- security-advisories@github.com (x_refsource_CONFIRM)
- security-advisories@github.com (x_refsource_MISC)
Frequently asked questions
- What is CVE-2026-48714?
- CVE-2026-48714 is a critical-severity vulnerability in I18next I18next-http-middleware, classified under Improperly Controlled Modification of Object Prototype Attributes (Prototype Pollution). CVSS score: 9.1/10. Published 2026-06-15.
- How severe is CVE-2026-48714?
- Critical severity. CVSS v3 base score is 9.1 out of 10.