Open Redirect in n8n Workflow Automation Platform

Executive Summary

CVE-2026-126386 is an open redirect vulnerability in n8n, an open-source workflow automation tool. It exists in the MCP OAuth Dynamic Client Registration feature, which is enabled by default without authentication. Attackers can register an OAuth client with a malicious redirect_uri and craft authorization URLs that redirect victims to attacker-controlled sites before n8n's validation checks occur. This turns the n8n instance into an open redirector, enabling phishing attacks.

The vulnerability affects n8n versions before 1.123.89, 2.45.5, 2.46.1, and 3.0.1. Exploitation requires victim interaction—users must click a crafted link. No tokens or session data are exposed in the redirect.

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Detection Guidance

To detect this vulnerability, check if your n8n instance is running a vulnerable version (before 1.123.89, 2.45.5, 2.46.1, or 3.0.1). Inspect network traffic for requests to /mcp-oauth/register or /mcp-oauth/authorize endpoints with suspicious redirect_uri parameters. Use tools like curl to test if the endpoint accepts arbitrary redirect URIs: curl -X POST http://<n8n-instance>/mcp-oauth/register -d '{"redirect_uri":"http://attacker.com"}'.

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Impact Analysis

This vulnerability can impact you by enabling phishing attacks. Attackers can trick you into clicking a malicious link that redirects you to a fake website designed to steal your credentials or sensitive information. Since the redirect happens before n8n's validation checks, you may unknowingly be sent to an attacker-controlled site.

The impact is limited to redirection; no tokens or session data are exposed. However, successful phishing could lead to unauthorized access to your accounts or data. The attack requires no privileges, has low complexity, and relies on user interaction.

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Mitigation Strategies

Upgrade n8n to a patched version (1.123.89 or later, 2.45.5 or later, 2.46.1 or later, or 3.0.1 or later). Restrict access to the vulnerable endpoints by blocking unauthenticated requests to /mcp-oauth/register and /mcp-oauth/authorize via network controls. Limit instance access to trusted users only and educate users to avoid clicking unsolicited links.

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