CVE-2026-65594

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

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.

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.

The application does not correctly enforce access controls, allowing a principal to access resources or operations beyond their granted permissions. Typical impact: unauthorized data access or execution of privileged operations.

Kodem intelligence

Already deployed Kodem?

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.

1. What is CVE-2026-65594? CVE-2026-65594 is a medium-severity incorrect authorization vulnerability in n8n (npm), affecting versions >= 2.30.0, < 2.30.1. It is fixed in 2.30.1, 2.29.8. The application does not correctly enforce access controls, allowing a principal to access resources or operations beyond their granted permissions.
2. Which versions of n8n are affected by CVE-2026-65594? n8n (npm) versions >= 2.30.0, < 2.30.1 is affected.
3. Is there a fix for CVE-2026-65594? Yes. CVE-2026-65594 is fixed in 2.30.1, 2.29.8. Upgrade to this version or later.
4. Is CVE-2026-65594 exploitable, and should I be worried? Whether CVE-2026-65594 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
5. What actually determines whether CVE-2026-65594 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
6. How do I fix CVE-2026-65594?
   • Upgrade n8n to 2.30.1 or later
   • Upgrade n8n to 2.29.8 or later

Other vulnerabilities in n8n