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HIGH · 7.5

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 application accesses `req.headersDistinct`. When this occur...

Vulnerability 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 Score

7.5

HIGH

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH

Related Weaknesses (CWE)

CWE-770

References

FAQ

What is CVE-2026-21710?

CVE-2026-21710 is a vulnerability with a CVSS score of 7.5 (HIGH). 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 occur...

How severe is CVE-2026-21710?

CVE-2026-21710 has been rated HIGH with a CVSS base score of 7.5/10. Review the CVSS metrics above for detailed severity breakdown.

Is there a patch for CVE-2026-21710?

Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.