CVE-2026-42230: n8n

Medium severity, CVSS 6.1. EPSS: 0.3% chance of exploitation in the next 30 days.

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.

Affected products

• n8n n8n: before 1.123.32 (fixed in 1.123.32); from 2.17.0, before 2.17.4 (fixed in 2.17.4); version 2.18.0 only

Published 2026-05-04. Last modified 2026-06-17.