CVE-2026-42230

n8n: Open Redirect in MCP OAuth Consent Flow

State: Published
Severity: 5.1 Medium
Published: May 4, 2026
Updated: May 4, 2026
Reserved: Apr 25, 2026

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.

Scores

CVSS	Score	Vector	Source
4.0	5.1 Medium	CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:L/VI:N/VA:N/SC:L/SI:N/SA:N	GitHub_M

Weaknesses

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

Affected Products

Product	Versions
n8nn8n-io	< 1.123.32Affected >= 2.17.0, < 2.17.4Affected >= 2.18.0, < 2.18.1Affected

References

https://github.com/n8n-io/n8n/security/advisories/GHSA-f6x8-65q6-j9m9

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