GHSA-hh89-3r9w-qj3j: n8n: Unauthenticated Persistent Storage Exhaustion via OAuth Dynamic Client Registration Endpoint

Summary

The n8n OAuth Dynamic Client Registration endpoints checked field sizes only for `redirect_uris`, leaving `client_name` and `grant_types` bounded by presence checks alone. An unauthenticated remote caller could submit arbitrarily large values in either field, and they were persisted to the database, so repeated registrations grew persistent storage without limit.

Mitigation

Fixed in n8n versions 2.37.7 and 2.38.2; upgrade to one of these or later. The patch caps `client_name` at its column length and limits `grant_types` to the grant types the server implements. Temporary workarounds: restrict network access to trusted clients, place the instance behind a reverse proxy enforcing request body size limits below the default 16 MiB, and monitor database growth and audit the `oauth_clients` table. The source states these workarounds do not fully remediate the risk.

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.

• n8nnpmDeclares an LLM dependency

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