GHSA-gv7g-jm28-cr3m: n8n: Expression sandbox escape via arrow-function bodies enabling command execution

n8n evaluates expressions, the {{ }} snippets in node fields, inside a sandbox that is meant to stop them reaching the host. Expressions that put code in arrow-function bodies get past that sandbox (CWE-94, code injection). The result is unintended system command execution on the machine running n8n.

The attacker needs an account that can create or modify workflows. That is a common right for team members. No user interaction is needed, and the CVSS 4.0 vector rates confidentiality, integrity and availability impact as high on the vulnerable system.

In practice, a workflow editor becomes a shell user for the n8n service account. From there they can read the credentials n8n stores, environment variables and API keys, and touch anything the host can reach. n8n instances usually hold keys to many other services, so one compromised editor can open a wide set of systems. The advisory gives no payload details.

Affected: n8n below 2.31.5, and 2.32.0. Instances where untrusted or semi-trusted people can create or edit workflows are the most exposed. The advisory names no 1.x release as affected or fixed.

Check the version:

npm ls n8n

For Docker, check the image tag or the version in the UI.

Upgrade to n8n 2.31.5 or 2.32.1, or later. For an npm install, run npm install [email protected].

Temporary mitigations from the advisory, neither of which fully removes the risk:

• Restrict instance access to fully trusted users.
• Restrict workflow creation and editing to fully trusted users.

After upgrading, treat credentials on a multi-user instance as exposed if an untrusted editor had access, and rotate them.

The advisory gives no log signature. Review workflows created or edited by non-admin users for expressions that contain arrow functions (=>) inside {{ }} fields, especially in fields where a plain value is expected. Look for child processes spawned by the n8n process, such as shells or network tools, and for outbound connections from the n8n host that your workflows do not explain. Check for new credentials, API keys or users created around the time of suspicious edits.

Impact

An authenticated user with permission to create or modify workflows could abuse crafted expressions using arrow functions to bypass the expression sandbox, triggering unintended system command execution on the host running n8n.

Patches

The issue has been fixed in n8n versions 2.31.5 and 2.32.1. Users should upgrade to one of these versions or later to remediate the vulnerability.

Workarounds

If upgrading is not immediately possible, administrators should consider the following temporary mitigations:

• Restrict n8n instance access to fully trusted users only.
• Restrict workflow creation and editing permissions to fully trusted users only.

These workarounds do not fully remediate the risk and should only be used as short-term mitigation measures.