PublicCVE

CVE-2026-21710

HIGH7.5Denial of service

Description

A flaw in Node.js HTTP request handling causes an uncaught `TypeError` when a request is received with a header named `__proto__` and the application accesses `req.headersDistinct`. When this occurs, `dest["__proto__"]` resolves to `Object.prototype` rather than `undefined`, causing `.push()` to be called on a non-array. This exception is thrown synchronously inside a property getter and cannot be intercepted by `error` event listeners, meaning it cannot be handled without wrapping every `req.headersDistinct` access in a `try/catch`. * This vulnerability affects all Node.js HTTP servers on **20.x, 22.x, 24.x, and v25.x**

CVSS breakdown

CVSS 3.1
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

Affected products

Updated 5m ago · 8 sources