CVE-2026-86076

Undergoing Analysis Undergoing Analysis - In Progress

Prototype Pollution in n8n Workflow Automation

Publication date: 2026-09-08

Last updated on: 2026-09-11

Assigner: GitHub, Inc.

Description

n8n is an open source workflow automation platform. Prior to 1.123.76, 2.37.7, and 2.38.2, the expression compiler sanitizer resolved through dynamically scoped this and did not reject reserved class member names. A class field named __sanitize could rebind the sanitizer and reach the Function constructor, enabling backend code execution and editor-preview JavaScript execution. The affected AST hook is PrototypeSanitizer in packages/workflow/src/expression-sandboxing.ts. This issue is fixed in versions 1.123.76, 2.37.7 and 2.38.2.

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-09-08

Last Modified

2026-09-11

Generated

2026-09-29

AI Q&A

2026-09-09

EPSS Evaluated

2026-09-27

NVD

CVE-2026-86076

EUVD

EUVD-2026-74280

Affected Vendors & Products

Vendor	Product	Version / Range
n8n	n8n	From 2.38.0 (inc) to 2.38.2 (exc)
n8n	n8n	to 1.123.76 (exc)
n8n	n8n	From 2.0.0 (inc) to 2.37.7 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-94	The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment.

Attack-Flow Graph

Executive Summary

This vulnerability in n8n allows an attacker to bypass the expression sandbox by rebinding the sanitizer through a class field named __sanitize. This grants access to the Function constructor, enabling arbitrary code execution on the backend or in the editor preview for users opening malicious workflows.

Detection Guidance

To detect this vulnerability, check the installed version of n8n. Run commands like 'n8n --version' or inspect package.json for the version. If the version is below 1.123.76, 2.37.7, or 2.38.2, the system is vulnerable.

Impact Analysis

If exploited, this vulnerability could allow an attacker to execute code on your n8n server or run JavaScript in the browser of any user who opens a malicious workflow. This could lead to data breaches, unauthorized access, or system compromise.

Compliance Impact

This vulnerability could lead to unauthorized data access or exfiltration, violating GDPR's data protection requirements and HIPAA's safeguards for protected health information. Compliance may be compromised if sensitive data is exposed due to exploitation.

Mitigation Strategies

Immediately upgrade n8n to versions 1.123.76, 2.37.7, or 2.38.2 or later. As temporary measures, restrict instance access to trusted users, limit workflow permissions, audit expressions, and set N8N_EXPRESSION_ENGINE=vm.

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