GHSA-xvxq-x6hr-xc2c: 
JavaScript vulnerability analysis and mitigation

Impact

Several validation, search, workflow update, audit and telemetry code paths did work or allocated memory that grew much faster than their input. One authenticated request with crafted input, or a crafted response from an n8n URL the caller controls, could block the Node.js event loop for seconds to minutes, or exhaust the heap and stop the process.

• stdio and single-tenant HTTP mode: only the caller's own server process is affected.
• Multi-tenant HTTP mode (ENABLE_MULTI_TENANT=true): one tenant can stall or stop the process that serves all tenants. Sessions held in memory are lost when the process stops. No data is exposed or changed.

Affected versions

n8n-mcp 2.99.0 and earlier.

Patched versions

2.99.1. It bounds input and response sizes on these paths and replaces the slow checks with linear-time ones.

Workarounds

• Run n8n-mcp in stdio mode, or as one process per tenant, instead of multi-tenant HTTP mode.
• Restrict who can reach the HTTP endpoint.
• Run the server under a supervisor that restarts it, such as Docker restart: unless-stopped.

Credit

Found in an internal security review.