CVE-2026-42230
Description
n8n is an open source workflow automation platform. Prior to versions 1.123.32, 2.17.4, and 2.18.1, the /mcp-oauth/register endpoint accepted OAuth client registrations without authentication, allowing arbitrary redirect_uri values to be registered. When a user denies the MCP OAuth consent dialog, the handleDeny handler redirects the user to the registered redirect_uri without validation, enabling an open redirect to an attacker-controlled URL. An attacker can craft a phishing link and send it to a victim; if the victim clicks "Deny" on the consent page, they are silently redirected to an external site. This issue has been patched in versions 1.123.32, 2.17.4, and 2.18.1.
How to fix
- n8n n8n1.123.32, 2.17.4 or later
- n8n1.123.32, 2.18.1, 2.17.4 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| n8n n8n | v < 1.123.32, 2.17.0 ≤ v < 2.17.4, 2.18.0 | 1.123.32, 2.17.4 |
| n8nnpm | v < 1.123.32, 2.18.0 ≤ v < 2.18.1, 2.0.0 ≤ v < 2.17.4 | 1.123.32, 2.18.1, 2.17.4 |
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