CVE-2026-41690

8.6 highEPSS 0.3%

18next-http-middleware is a middleware to be used with Node.js web frameworks like express or Fastify and also for Deno. Versions prior to 3.9.3 allow an unauthenticated HTTP client to pollute Object.prototype in the Node.js process hosting the middleware, via two unvalidated entry points that reach internal object-key writes: getResourcesHandler and missingKeyHandler. This can break authorisation checks (if (user.isAdmin) returning true for any user), cause type-confusion DoS, and depending on downstream code it can be chained into RCE.

CVSS 3.1: 8.6CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:L
EPSS: 0.3% chance of exploitation in the next 30 days; higher than 23% of CVEs (scores of 2026-10-26)
CWEs: CWE-22, CWE-1321
Published: 2026-05-08
Modified: 2026-10-26
Record from: the NVD, synced 2026-10-26

Packages (OSV)

Advisory	Ecosystem	Package	Affected	Fixed in
GHSA-5fgg-jcpf-8jjw	npm	i18next-http-middleware	<3.9.3	3.9.3

References

https://github.com/i18next/i18next-http-middleware/security/advisories/GHSA-5fgg-jcpf-8jjw

Check your stack JSON