CVE-2026-65594

Analyzed Analyzed - Analysis Complete

OAuth Token Misuse in n8n Workflow

Publication date: 2026-07-22

Last updated on: 2026-07-27

Assigner: VulnCheck

Description

n8n before 2.29.8 and 2.30.x before 2.30.1 (affected from 2.27.0, when the OAuth 2.1 consent and token-issuance flow was introduced) does not verify that the authenticated user has access to the workflow referenced as the OAuth resource. On instances with at least one active MCP Server Trigger workflow configured with n8n OAuth2 authentication, a member-level user can register an OAuth client, self-approve consent for another user's workflow, and obtain a valid token. The workflow then runs in the owner's project context with the owner's stored credentials, and the attacker can set tool inputs and read outputs (potentially including data from the owner's connected integrations), breaking user and project isolation.

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-07-22

Last Modified

2026-07-27

Generated

2026-08-11

AI Q&A

2026-07-22

EPSS Evaluated

2026-08-10

NVD

CVE-2026-65594

EUVD

EUVD-2026-47638

Affected Vendors & Products

Vendor	Product	Version / Range
n8n	n8n	2.30.0
n8n	n8n	2.30.0
n8n	n8n	From 2.27.0 (inc) to 2.29.8 (exc)
n8n	n8n	From 2.27.0 (inc) to 2.29.8 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-863	The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check.

Attack-Flow Graph

Executive Summary

This vulnerability in n8n versions before 2.30.1 and 2.29.8 allows a member-level user to bypass OAuth authorization checks. The flaw was introduced in version 2.27.0 with the OAuth 2.1 consent flow. An attacker can register an OAuth client, self-approve consent for another user's workflow, and obtain a valid token to execute the workflow in the owner's project context with the owner's credentials.

Detection Guidance

To detect this vulnerability, check if your n8n instance is running version 2.27.0 or later and has at least one active MCP Server Trigger workflow configured with n8n OAuth2 authentication. Review user permissions to identify member-level users who may have registered OAuth clients or self-approved consents.

Impact Analysis

An attacker could set tool inputs and read outputs of the workflow, potentially accessing sensitive data from the owner's connected integrations. The attack breaks user and project isolation, allowing unauthorized access to workflows and data. The vulnerability requires an instance with at least one active MCP Server Trigger workflow using n8n OAuth2 authentication.

Compliance Impact

This vulnerability could lead to unauthorized access to sensitive data, violating confidentiality requirements in GDPR and HIPAA. It may result in data breaches, non-compliance with data protection regulations, and potential legal consequences due to compromised user and project isolation.

Mitigation Strategies

Immediately upgrade n8n to version 2.29.8 or 2.30.1 or later. Restrict instance access to fully trusted users only. Audit active workflows using MCP Server Trigger with n8n OAuth2 authentication and consider switching to a different authentication method or deactivating them until patched.

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