What is the CVSS score of CVE-2026-26021?

CVE-2026-26021 has a CVSS 3.1 base score of 9.8 (Critical). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. EPSS exploitation probability: 0.0%.

Which versions of Node.js are affected by CVE-2026-26021?

A critical prototype pollution vulnerability in Set-In (CVSS 9.8) allows unauthenticated attackers to modify core application objects, potentially leading to unauthorized access, data manipulation,…. A patch is available.

Is there a public PoC exploit available for CVE-2026-26021?

Yes, a public proof-of-concept exploit is available for CVE-2026-26021. Prioritise patching immediately. EPSS: 0.0%.

How to fix or mitigate CVE-2026-26021?

Within 24 hours: Inventory all systems running Set-In and assess exposure; disable Set-In in non-production environments if patching will take longer. Within 7 days: Apply the available vendor patch to all production systems following change management procedures; validate patch deployment. Within 30 days: Conduct post-patch verification, review application logs for exploitation attempts, and update asset management records.

Node.js CVE-2026-26021

CRITICAL

Improperly Controlled Modification of Object Prototype Attributes (Prototype Pollution) (CWE-1321)

2026-02-11 security-advisories@github.com

GHSA-2c4m-g7rx-63q7

Node.js Set In Set In Project

9.8

CVSS 3.1 · GitHub Advisory

Severity by source

GitHub Advisory PRIMARY

9.8 CRITICAL

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

Primary rating from GitHub Advisory · only source for this CVE.

CVSS VectorGitHub Advisory

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Lifecycle Timeline

Analysis Generated

Mar 12, 2026 - 22:02 vuln.today

PoC Detected

Feb 13, 2026 - 21:43 vuln.today

Public exploit code

Patch released

Feb 13, 2026 - 21:43 nvd

Patch available

CVE Published

Feb 11, 2026 - 22:15 nvd

CRITICAL 9.8

DescriptionGitHub Advisory

set-in provides the set value of nested associative structure given array of keys. A prototype pollution vulnerability exists in the the npm package set-in (>=2.0.1, < 2.0.5). Despite a previous fix that attempted to mitigate prototype pollution by checking whether user input contained a forbidden key, it is still possible to pollute Object.prototype via a crafted input using Array.prototype. This has been fixed in version 2.0.5.

AnalysisAI

Prototype pollution in set-in npm package allows modification of Object prototype. PoC and patch available.

Technical ContextAI

CWE-1321 prototype pollution through nested key assignment.

RemediationAI

Update set-in.

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CVE-2026-26021 vulnerability details – vuln.today

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Node.js CVE-2026-26021

Severity by source

CVSS VectorGitHub Advisory

Lifecycle Timeline

DescriptionGitHub Advisory

AnalysisAI

Technical ContextAI

RemediationAI

More in Node.js

Same weakness CWE-1321 – Improperly Controlled Modification of Object Prototype Attributes (Prototype Pollution)

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External POC / Exploit Code