CVE-2026-41690
CWE-22Published: May 8, 2026· Updated: May 12, 2026
Official 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.
Technical Analysis
CVE-2026-41690 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.
The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.
A successful exploit results in full integrity compromise (data manipulation), with a CVSS base score of 8.6.
CVSS v3.1 Vector Breakdown
Affected Vendors & Products
Exploit & PoC Resources
All References (1)
Quick Facts
Related CVEs (CWE-22)
Recommended Actions
- →Apply vendor patches immediately
- →Monitor CVE-2026-41690 in threat intel feeds
- →Review IDS/IPS signatures for exploitation attempts