VULNERABILITY INTELLIGENCE

CVE-2026-21710

CVSS score7.5 HIGH
EPSS probability25.44%
CISA KEVNot currently listed
Published2026-03-30
Last modified2026-08-19
CVSS vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

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**

Weakness classification

  • 134c704f-9b21-4f2e-91b3-4a467353bcc0: CWE-770
  • 0b0ca135-0b70-47e7-9f44-1890c2a1c46c: CWE-843

Primary references