CVE-2026-110842

Deferred Deferred - Pending Action

Prototype Pollution in n8n MCP Workflow-Validation

Publication date: 2026-10-14

Last updated on: 2026-10-15

Assigner: VulnCheck

Description

n8n before 2.41.4 and 2.42.x before 2.42.1 contains a prototype pollution vulnerability in the MCP workflow-validation tool, whose interpreter evaluates caller-supplied code in the main process, reads inherited properties, and permits assignment onto shared prototypes. An authenticated member holding only a workflow:read grant can replace a built-in method with one returning a truthy value so server-side permission checks accept unheld scopes, enabling takeover of owner accounts not protected by MFA.

CVSS Scores

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Meta Information

Published

2026-10-14

Last Modified

2026-10-15

Generated

2026-10-19

AI Q&A

2026-10-15

EPSS Evaluated

2026-10-18

NVD

CVE-2026-110842

EUVD

EUVD-2026-101725

Affected Vendors & Products

Vendor	Product	Version / Range
n8n-io	n8n	0
n8n-io	n8n	2.42.0

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-1321	The product receives input from an upstream component that specifies attributes that are to be initialized or updated in an object, but it does not properly control modifications of attributes of the object prototype.

Attack-Flow Graph

Executive Summary

n8n versions before 2.41.4 and 2.42.x before 2.42.1 have a prototype pollution flaw in the MCP workflow-validation tool. This tool executes user-supplied code in the main process, reads inherited properties, and allows modifying shared prototypes. An attacker with only workflow:read access can replace a built-in method to return a truthy value, bypassing server-side permission checks and enabling account takeover of owners without MFA protection.

Detection Guidance

To detect this vulnerability, check the installed version of n8n. Run: n8n --version. If the version is below 2.41.4 or 2.42.1, the system is vulnerable. Additionally, review MCP workflow-validation tool usage and audit workflow:read OAuth grants for unauthorized access.

Impact Analysis

If you use affected n8n versions, an authenticated attacker with minimal privileges could escalate their access to take over owner accounts, even those protected by MFA. This could lead to unauthorized workflow execution, data access, or system control depending on the compromised account's permissions.

Compliance Impact

This vulnerability could lead to unauthorized access to sensitive data, violating GDPR's data protection principles or HIPAA's access controls. Organizations using affected n8n versions may face compliance breaches, potential fines, and reputational damage due to insufficient access controls.

Mitigation Strategies

Upgrade n8n to version 2.41.4 or later if using the 2.41.x branch, or to version 2.42.1 or later if using the 2.42.x branch. This vulnerability is patched in these versions.

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