CVE-2026-42230

Summary

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 Software

VendorProductVersion RangeStatus
n8n-ion8n< 1.123.32affected
n8n-ion8n>= 2.17.0, < 2.17.4affected
n8n-ion8n>= 2.18.0, < 2.18.1affected

Weaknesses

  • CWE-601: CWE-601: URL Redirection to Untrusted Site ('Open Redirect')

ADP Enrichment

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: none
    • Automatable: no
    • Technical Impact: partial

References