mcp-memory-service Missing Authentication on /api/documents Routes

Technical Analysis

The vulnerability stems from an inconsistent authentication boundary: the /api/memories endpoints correctly enforce the MCP_API_KEY/OAuth dependency, but the /api/documents/* endpoints were implemented without wiring in the same authentication middleware. This allows any network-reachable attacker to POST arbitrary content directly into the vector/document memory store, GET stored document content to exfiltrate potentially sensitive context, or DELETE existing memories belonging to legitimate authenticated users. Because agents consuming this memory service trust retrieved documents as contextual grounding, injected content can later be surfaced to an LLM as trusted memory, effectively achieving remote memory poisoning and downstream prompt injection with no credentials required. The entry point is purely network-level HTTP access to the exposed API, crossing the trust boundary between the memory-service backend and any agent or user relying on its integrity.

Affected Systems

mcp-memory-service; protocols: MCP

Detection Signatures

• Unauthenticated HTTP requests to /api/documents/* endpoints in access logs (no Authorization/API-key header present)
• Requests to /api/documents succeeding with 2xx while equivalent /api/memories requests without credentials return 401/403
• Unexpected or anomalous document content appearing in agent memory retrieval results
• Unexplained deletion of memory entries with no corresponding authenticated user action in audit logs
• High-frequency POST/DELETE traffic to /api/documents from unfamiliar source IPs

Remediation Steps

1. 1

   Upgrade immediately

   Update mcp-memory-service to version 10.67.1 or later, which fixes the missing authentication dependency on /api/documents/* routes.

2. 2

   Audit exposed memory content

   Review stored documents and memories for signs of unauthorized insertion, tampering, or deletion that may have occurred while the endpoint was exposed.

3. 3

   Enforce network-level restrictions

   Until patched, restrict network access to the memory-service instance via firewall rules, VPN, or reverse-proxy authentication as a compensating control.

4. 4

   Add consistent auth middleware testing

   Implement automated tests that verify every API route requires authentication when API keys or OAuth are configured, to prevent future inconsistent enforcement.

5. 5

   Rotate credentials and monitor

   Rotate any API keys used with the service and monitor logs for historical unauthenticated access to /api/documents endpoints.