CVE-2026-21710: Node.js

High severity, CVSS 7.5. EPSS: 25% chance of exploitation in the next 30 days.

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**

Affected products

• Node.js Node.js: up to and including 20.20.1; from 22.0.0, up to and including 22.22.1; from 24.0.0, up to and including 24.14.0; from 25.0.0, up to and including 25.8.1
• Red Hat Enterprise Linux: version 8.0 only; version 9.0 only; version 10.0 only
• Red Hat Enterprise Linux Eus: version 9.4 only; version 9.6 only; version 10.0 only

Published 2026-03-30. Last modified 2026-08-19.