The vulnerability involves insertion of sensitive information into server logs by n8n-mcp versions before 2.47.11 when operating in HTTP transport mode. Incoming POST /mcp requests have their metadata logged regardless of authentication outcome, causing bearer tokens from the Authorization header, tenant API keys from the x-n8n-key header, and JSON-RPC payloads to be written to logs. This can lead to unintended disclosure if logs are collected, forwarded, or accessible beyond the intended trust boundary. The vulnerability does not allow bypassing access controls, as unauthorized requests still receive 401 Unauthorized responses. The issue is fixed in version 2.47.11.

Sensitive authentication tokens and request payloads may be exposed through server logs if those logs are accessible to unauthorized parties. This could lead to information disclosure risks, especially in environments where logs are aggregated, forwarded externally, or accessible by support or operations personnel. There is no impact on system integrity or availability, and no bypass of access controls occurs.

Upgrade n8n-mcp to version 2.47.11 or later, where this logging behavior has been corrected. Until upgraded, restrict access to server logs to trusted personnel only and avoid forwarding logs containing sensitive request metadata to external systems. Patch status is not explicitly stated as 'official-fix' in the vendor advisory, but the description confirms the issue is fixed in version 2.47.11.