CVE-2026-27578

n8n is an open source workflow automation platform. Prior to versions 2.10.1, 2.9.3, and 1.123.22, an authenticated user with permission to create or modify workflows could inject arbitrary scripts into pages rendered by the n8n application using different techniques on various nodes (Form Trigger node, Chat Trigger node, Send & Wait node, Webhook Node, and Chat Node). Scripts injected by a malicious workflow execute in the browser of any user who visits the affected page, enabling session hijacking and account takeover. The issues have been fixed in n8n versions 2.10.1 and 1.123.21. Users should upgrade to one of these versions or later to remediate the vulnerability. If upgrading is not immediately possible, administrators should consider the following temporary mitigations. Limit workflow creation and editing permissions to fully trusted users only, and/or disable the Webhook node by adding `n8n-nodes-base.webhook` to the `NODES_EXCLUDE` environment variable. These workarounds do not fully remediate the risk and should only be used as short-term mitigation measures.

A threat actor with access to a low-privilege n8n account (e.g., a contractor, a compromised service account, or an insider) creates or modifies a workflow using the Chat Trigger or Webhook node, embedding a JavaScript payload in the node configuration. When an admin opens the n8n dashboard and navigates to the affected workflow, the script executes in their browser — stealing the session cookie or Bearer token. The attacker replays the stolen token to authenticate as admin, then enumerates all stored credentials (OpenAI API keys, database passwords, Slack tokens), exfiltrates them, and modifies production AI workflows to insert silent data exfiltration steps or prompt injection instructions that affect downstream LLM behavior.