CVE-2026-65594 n8n-io CVE debrief

Who should care

Users of n8n workflow automation tool, especially those with MCP Server Trigger workflows configured with n8n OAuth2 authentication, should verify their instances and apply patches to prevent unauthorized access. This includes reviewing workflow configurations, monitoring user activities, and implementing additional access controls.

Technical summary

n8n versions before 2.29.8 and 2.30.x before 2.30.1 are vulnerable to an authorization bypass. An attacker can register an OAuth client, self-approve consent for another user's workflow, and obtain a valid token, allowing them to execute the workflow in the owner's project context with the owner's stored credentials. This can lead to unauthorized access to sensitive data and potential lateral movement.

Defensive priority

Medium priority for n8n users, especially those with active MCP Server Trigger workflows and OAuth2 authentication.

Recommended defensive actions

• Verify n8n instance version and apply patches to 2.29.8 or 2.30.1
• Review and restrict OAuth client registrations
• Monitor workflow executions and user activities
• Implement additional access controls and logging
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented

Evidence notes

The vulnerability was introduced in n8n version 2.27.0 with the OAuth 2.1 consent and token-issuance flow. Official patches are available in versions 2.29.8 and 2.30.1. Evidence limits suggest that defenders verify instances with at least one active MCP Server Trigger workflow configured with n8n OAuth2 authentication. Defensive verification tasks include reviewing workflow configurations, monitoring user activities, and implementing additional access controls.

Official resources