CVE-2026-21710

7.5 HIGH 25% exploit odds Fix listed Denial of service

What it is

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**

At a glance

Exploitability: Can be exploited over the network without logging in. High risk of service disruption.
Exploit odds: 25.4% chance of exploitation in the next 30 days (EPSS). Higher than most.
Fix: A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

2026-03-30 20:16 UTC PublishedDisclosed publicly on CVE.org and NVD
2026-08-19 14:32 UTC Last updatedMost recent change to the record

Why it ranks here

Exploited in the wild: no, CISA does not list it.
Exploit odds: 25.4% in the next 30 days (EPSS).
Severity: 7.5 HIGH (CVSS).
Fix: a patch or advisory is linked.

Details

Published: 2026-03-30 20:16 UTC
Last modified: 2026-08-19 14:32 UTC
Exploit probability: 25.4% · EPSS, next 30 days
Weakness: CWE-770 · Allocation without limits
Record status: Analyzed

Affected

Nodejs node.js ≤ 20.20.1
Nodejs node.js ≤ 22.22.1
Nodejs node.js ≤ 24.14.0
Nodejs node.js ≤ 25.8.1
Redhat Enterprise Linux 8.0
Redhat Enterprise Linux 9.0
Redhat Enterprise Linux 10.0
Redhat Enterprise Linux Eus 9.4

Attack profile CVSS 3.1 · 7.5

Attack vector: Network
Complexity: Low
Privileges needed: None
User interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: None
Availability: High

Raw vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2026-21710.md and follow it. Check whether this project is affected by CVE-2026-21710. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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Fix and advisories

https://nodejs.org/en/blog/vulnerability/march-2026-security-releases

References

NVD record · CVE.org record