GHSA-537j-gqpc-p7fq: n8n Vulnerable to XSS via MCP OAuth client

Summary

An unauthenticated attacker can register a malicious MCP OAuth client with a crafted client_name. When a second user revokes access after a victim authorized the OAuth consent dialog, a toast notification renders the injected script. Clicking the link runs arbitrary JavaScript in the victim's authenticated n8n browser session, enabling credential and session token theft, workflow manipulation, or privilege escalation.

Mitigation

Fixed in n8n version 2.14.2; users should upgrade to this version or later. Until then, administrators should consider restricting access to the n8n instance and the MCP OAuth registration endpoint to trusted users only, and disabling MCP server functionality if it is not actively required. The source states these workarounds do not fully remediate the risk and are only short-term measures.

Affected packages in the Exposure Registry

Matched by package name and ecosystem. Each entry shows whether the package delegates to a language model and how many tracked packages depend on it.

• n8nnpmLLM dependency since 2026-02-10

Topics

• Model Context Protocol

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