CVE-2026-42230

Name of the Vulnerable Software and Affected Versions n8n versions prior to 1.123.32 n8n versions prior to 2.17.4 n8n versions prior to 2.18.1

Description The '/mcp-oauth/register' endpoint allows OAuth client registrations without authentication, which permits the registration of arbitrary redirect uri values. When a user denies the MCP OAuth consent dialog, the handleDeny() handler redirects the user to the registered redirect uri without validation. This creates an open redirect, allowing an attacker to use a phishing link to silently redirect a victim to an external, attacker-controlled site if the victim clicks "Deny" on the consent page.

Recommendations Update to version 1.123.32. Update to version 2.17.4. Update to version 2.18.1.