CVE-2026-41690HIGH 8.6EPSS p22.6%
CVE-2026-41690CVE-2026-41690
Description
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.
Scoring
| CVSS 3.1 | 8.6 (HIGH) |
| Vector | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:L |
| EPSS | 0.31% probability of exploitation · percentile 22.6% · 2026-06-18T12:00:27Z |
| Published | 2026-05-08 |
| Last modified | 2026-05-12 |
Underlying weaknesses· 2
References
2
| Type | Target | Confidence | Tier |
|---|---|---|---|
| Weakness | Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')cwe-1321 | 0% | live |
| Weakness | Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')cwe-22 | 0% | live |
Related by meaning· 6
Nearest entities by semantic similarity across the cs-graph corpus.