A crafted workflow can pollute Object.prototype allowing unauthenticated requests to be treated as privileged. This results in information disclosure of all users and projects an elevation of privilege to an unauthenticated attacker. The weakness is a prototype-pollution injection (CWE-1321).

The vulnerability affects n8n-io:n8n. Any instance running a version earlier than 1.123.61, 2.27.4, or 2.28.1 is susceptible. The affected component is the workflow API that accepts create, update, or import operations.

The CVSS score of 7.1 indicates a moderate to high risk. The EPSS score of < 1% shows a very low but non-zero likelihood of exploitation, and the vulnerability is not listed in the CISA KEV catalog. Exploitation requires an authenticated user with workflow:create permission; the attacker crafts a malicious workflow, saves or imports it, and then performs unauthenticated requests that are treated as privileged. The attack path relies on the API endpoint that accepts workflow data and permits prototype pollution.