CVE-2026-21710
Severity CVSS v4.0:
Pending analysis
Type:
Unavailable / Other
Publication date:
30/03/2026
Last modified:
01/04/2026
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`.<br />
<br />
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`.<br />
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* This vulnerability affects all Node.js HTTP servers on **20.x, 22.x, 24.x, and v25.x**
Impact
Base Score 3.x
7.50
Severity 3.x
HIGH