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.
Problem types
CWE-601: URL Redirection to Untrusted Site ('Open Redirect')
Product status
>= 2.17.0, < 2.17.4
>= 2.18.0, < 2.18.1
References
github.com/...io/n8n/security/advisories/GHSA-f6x8-65q6-j9m9