GHSA-q5xf-xhwf-cwqf CVE-2026-65594

n8n: Member-Level Users Can Execute Other Users' MCP Server Trigger Workflows via Missing OAuth Authorization Check

Medium npm

Severity: 0.0 / 10; Medium · CVSS 4.0
Exploit chance (EPSS): 0.44%; Chance of exploitation in the next 30 days. Higher than 38.29% of scored vulnerabilities.
Known exploited: No; Not in CISA's catalog
Weakness: CWE-863 Incorrect Authorization
Fix: 2.30.1; Upgrade n8n to this version or later

Description

Impact

The OAuth 2.1 consent and token-issuance flow introduced in n8n 2.27.0 does not verify that the authenticated user has access to the workflow referenced as the OAuth resource. A member-level user can register an OAuth client, self-approve consent for another user's n8n OAuth2-protected MCP Server Trigger workflow, and obtain a valid token for it.

The workflow runs in the owner's project context with the owner's stored credentials. The attacker sets the tool inputs and reads the outputs, which may include data from the owner's connected integrations, breaking user and project isolation. The resulting executions appear under the owner's account and are not visible to the attacker.

This issue only affects instances running n8n 2.27.0 or later where at least one active workflow uses an MCP Server Trigger node configured with n8n OAuth2 authentication.

Patches

The issue has been fixed in n8n versions 2.29.8 and 2.30.1. Users should upgrade to one of these versions or later to remediate the vulnerability.

Workarounds

If upgrading is not immediately possible, administrators should consider the following temporary mitigations:

Restrict n8n instance access to fully trusted users only.
Audit active workflows using the MCP Server Trigger with n8n OAuth2 authentication and consider switching to a different authentication method or deactivating them until the patch is applied.

These workarounds do not fully remediate the risk and should only be used as short-term mitigation measures.

Affected versions

npm

Package	Vulnerable	Fixed in
n8n	`>= 2.30.0, < 2.30.1`	`2.30.1`
n8n	`< 2.29.8`	`2.29.8`

How to fix

Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.

n8n npm → `2.30.1`

npm

npm install n8n@2.30.1

yarn

yarn add n8n@2.30.1

pnpm

pnpm add n8n@2.30.1

Severity breakdown

CVSS 4.0 0.0

CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:L/VA:N/SC:H/SI:L/SA:N

Attack vector: Network
Attack complexity: Low
Attack requirements: Present
Privileges required: Low
User interaction: None
Confidentiality (vulnerable system): Low
Integrity (vulnerable system): Low
Availability (vulnerable system): None
Confidentiality (subsequent systems): High
Integrity (subsequent systems): Low
Availability (subsequent systems): None

CVSS 3.1 6.5

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

Attack vector: Network
Attack complexity: Low
Privileges required: Low
User interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: None
Availability: None

Weakness

CWE-863: Incorrect Authorization

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.

How to prevent it

Architecture and Design: Divide the product into anonymous, normal, privileged, and administrative areas. Reduce the attack surface by carefully mapping roles with data and functionality. Use role-based access control (RBAC) [REF-229] to enforce the roles at the appropriate boundaries. Note that this approach may not protect against horizontal authorization, i.e., it will not protect a user from attacking others with the same role.
Architecture and Design: Ensure that access control checks are performed related to the business logic. These checks may be different than the access control checks that are applied to more generic resources such as files, connections, processes, memory, and database records. For example, a database may restrict access for medical records to a specific database user, but each record might only be intended to be accessible to the patient and the patient's doctor [REF-7].
Architecture and Design: Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, consider using authorization frameworks such as the JAAS Authorization Framework [REF-233] and the OWASP ESAPI Access Control feature [REF-45].
Architecture and Design: For web applications, make sure that the access control mechanism is enforced correctly at the server side on every page. Users should not be able to access any unauthorized functionality or information by simply requesting direct access to that page. One way to do this is to ensure that all pages containing sensitive information are not cached, and that all such pages restrict access to requests that are accompanied by an active and authenticated session token associated with a user who has the required permissions to access that page.
System Configuration, Installation: Use the access control capabilities of your operating system and server environment and define your access control lists accordingly. Use a "default deny" policy when defining these ACLs.

References

Advisories

nvd.nist.gov/vuln/detail/CVE-2026-65594

Packages

github.com/n8n-io/n8n

Timeline

Jul 22, 2026 Published
Oct 29, 2026 Last updated by the source
Nov 1, 2026 Latest EPSS score

Advisory	Severity	Why it's related
GHSA-v98v-ff95-f3cp n8n Vulnerable to Remote Code Execution via Expression Injection	High Known exploited	Also affects n8n
GHSA-qgpw-8g46-w95v n8n: Git Node branch.<name>.remote Config Key Bypasses Sandbox Path Restriction, Enabling Local Git Repository Read	Medium	Also affects n8n
GHSA-65xw-2v52-jhxc n8n: Cross-User Active Workflow ID and Lifecycle Event Disclosure via Missing userId Filter	Medium	Also affects n8n
GHSA-pq6c-vh67-xpm3 n8n: Log Streaming Event Destinations Decrypt Generic-Auth Credentials Without Ownership Check	Medium	Also affects n8n
GHSA-cqr2-h44g-v75v n8n: Cross-Tenant Project-Member PII Disclosure via Missing Per-Project Scope Check on Role Assignment Endpoints	Medium	Also affects n8n
GHSA-pf83-w3f9-8m37 n8n: Disabled OIDC SSO Endpoints Remain Active and Issue Valid Sessions	Medium	Also affects n8n
GHSA-6xcw-7xm6-48c6 n8n: Expression Sandbox Escape via Shared Builtin Tampering and Code-Printer Injection Leads to Code Execution	High	Also affects n8n
GHSA-34ff-336r-5q23 n8n: Domain-Restriction Bypass via Unguarded Model-Search Endpoint in OpenAI Chat Model Node	Medium	Also affects n8n

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