CVE WatchJul 15, 2026

CVE-2026-21710

A flaw in Node.js HTTP request handling causes an uncaught `TypeError` when a request is received with a header named `__proto__` and the ap

CVSS

7.5

High

EPSS

26.4%

p98

KEV

—

Exploit Today

0-100

Published: Mar 30, 2026 · Last modified: Jul 15, 2026 · CWE-770 · CWE-843

EPSS · 30d

26.4%EPSS · 30 days26.4%

2026-06-302026-07-16

Technical 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**

Official references

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