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**
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**
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Affected Vendors & Products
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Advisories
| Source | ID | Title |
|---|---|---|
 Debian DSA |
DSA-6183-1 | nodejs security update |
Fixes
Solution
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Workaround
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References
History
Mon, 30 Mar 2026 19:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| 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** | |
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cvssV3_0
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Projects
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MITRE
Status: PUBLISHED
Assigner: hackerone
Published:
Updated: 2026-03-30T19:07:28.558Z
Reserved: 2026-01-04T15:00:06.574Z
Link: CVE-2026-21710
Vulnrichment
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NVD
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Redhat
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OpenCVE Enrichment
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Weaknesses
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