CVE-2026-21710
Node.js HTTP Server Prototype Pollution 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**
INFO
Published Date :
March 30, 2026, 8:16 p.m.
Last Modified :
April 1, 2026, 2:24 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.0 | HIGH | [email protected] | ||||
| CVSS 3.0 | HIGH | MITRE-CVE |
Solution
- Update Node.js to a version that includes the fix.
- Avoid accessing req.headersDistinct directly.
- Wrap accesses in try/catch blocks if updates are not possible.
Public PoC/Exploit Available at Github
CVE-2026-21710 has a 5 public
PoC/Exploit available at Github.
Go to the Public Exploits tab to see the list.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-21710.
| URL | Resource |
|---|---|
| https://nodejs.org/en/blog/vulnerability/march-2026-security-releases |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-21710 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-21710
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
None
Python JavaScript
None
JavaScript
DSA and DLA for Debian last 14 days
Python
None
📡 PoC auto collect from GitHub. ⚠️ Be careful Malware.
security cve exploit poc vulnerability
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-21710 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-21710 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
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CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Mar. 31, 2026
Action Type Old Value New Value Added CWE CWE-770 -
New CVE Received by [email protected]
Mar. 30, 2026
Action Type Old Value New Value 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** Added CVSS V3 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Added Reference https://nodejs.org/en/blog/vulnerability/march-2026-security-releases