HTB App MCP

Local MCP server for Hack The Box App services via the HTB API v4 at:

https://labs.hackthebox.com/api/v4

This project does not use pyhackthebox: the client talks directly to HTB via httpx and authenticates with:

Authorization: Bearer <HTB_APP_TOKEN>

Do not confuse this with the official HTB CTF MCP at mcp.hackthebox.ai/v1/ctf/mcp/. This server is for HTB App/Labs content: Machines, Challenges, Sherlocks, Fortresses, Starting Point, Seasonal, and Pro Labs.

Current status

• Recommended transport: local Streamable HTTP MCP on http://127.0.0.1:8000/mcp.

• HTTP is stateless by default: restart the server without your MCP client getting stuck on Session not found.

• Recommended auth: MCP header Authorization: Bearer <HTB_APP_TOKEN>, no .env needed.

• Fallback: stdio + .env / environment variables.

• Exposed tools: 56.

Related MCP server: HackMD MCP Server

Setup

Prerequisites:

• Python 3.11+

• uv

• HTB App Token from app.hackthebox.com

Install dependencies:

uv sync

Recommended mode: HTTP with Authorization header

Start the server:

uv run htb-app-mcp --transport http --host 127.0.0.1 --port 8000

Configure your MCP client:

{
  "mcpServers": {
    "htb-app-mcp": {
      "url": "http://127.0.0.1:8000/mcp",
      "type": "http",
      "headers": {
        "Authorization": "Bearer <HTB_APP_TOKEN>"
      }
    }
  }
}

In this mode the token comes from the MCP client and is forwarded to HTB only. No .env required.

Restarting the server

HTTP is stateless by default, avoiding the Session not found issue. You can restart:

uv run htb-app-mcp --transport http --host 127.0.0.1 --port 8000

and the MCP client can reconnect without starting a new chat. If the client still uses an old connection, reload the MCP servers on the client side.

For protocol debugging you can force stateful mode:

uv run htb-app-mcp --transport http --stateful-http

Alternative mode: stdio

Stdio is useful when an MCP host wants to launch the local process directly.

Config:

{
  "mcpServers": {
    "htb-app-mcp": {
      "command": "uv",
      "args": ["--directory", "D:\\Sources\\htb-app-mcp", "run", "htb-app-mcp"],
      "env": {
        "HTB_API_TOKEN": "<HTB_APP_TOKEN>"
      }
    }
  }
}

You can also use .env as a local fallback:

cp .env.example .env
# edit .env and set HTB_API_TOKEN (or API_TOKEN)
uv run htb-app-mcp

.env is gitignored.

Tools

Resource:

htb://service-map

Prompt:

htb_target_workflow

HTB endpoints covered

The server uses verified real endpoints on labs.hackthebox.com/api/v4, including:

GET  /user/info
GET  /connection/status
GET  /user/connection/status
GET  /connections/servers?product=...
POST /connections/servers/switch/{vpnId}
GET  /access/ovpnfile/{vpnId}/0
GET  /access/ovpnfile/{vpnId}/0/1

GET  /search/fetch

GET  /machine/paginated
GET  /machine/profile/{machineSlug}
GET  /machine/active
GET  /machine/recommended
GET  /machines/{machineId}/tasks
POST /vm/spawn
POST /vm/terminate
POST /vm/extend
POST /vm/reset
POST /vm/reset/vote
POST /vm/reset/vote/accept
POST /machine/own

GET  /challenges
GET  /challenge/info/{challengeSlug}
GET  /challenge/categories/list
GET  /challenges/{challengeId}/download_link
POST /challenge/start
POST /challenge/stop
POST /container/start
POST /container/stop
POST /challenge/own

GET  /sherlocks
GET  /sherlocks/{sherlockId}/info
GET  /sherlocks/{sherlockId}/tasks
GET  /sherlocks/{sherlockId}/progress
GET  /sherlocks/{sherlockId}/play
GET  /sherlocks/{sherlockId}/download_link
POST /sherlocks/{sherlockId}/tasks/{taskId}/flag

GET  /fortresses
GET  /fortress/{fortressId}
GET  /fortress/{fortressId}/flags
POST /fortress/{fortressId}/flag
POST /fortress/{fortressId}/reset

GET  /season/list
GET  /season/machine/active
GET  /season/machines/{seasonId}
GET  /season/rewards/{seasonId}
GET  /season/user/rank/{seasonId}
GET  /season/user/{userId}/ranks
GET  /season/{players|teams}/leaderboard
GET  /season/{players|teams}/leaderboard/top/{seasonId}

GET  /sp/tiers/progress
GET  /sp/tier/{tierId}

GET  /prolabs
GET  /prolab/{prolabId}/overview
GET  /prolab/{prolabId}/machines
GET  /prolab/{prolabId}/flags
POST /prolab/{prolabId}/flag

Some older endpoints documented online now return 404 (e.g. /machine/list, /machines, /starting-point/machines).

Downloads

Supported downloads:

• OVPN: htb_download_ovpn

• Challenge ZIP: htb_download_challenge

• Sherlock ZIP: htb_download_sherlock

Defaults:

• directory: downloads

• ZIP password: hackthebox

• ZIP extraction: enabled for challenges and Sherlocks

• ZIP downloads serialized with a minimum interval to reduce 429 Too Many Requests

Change the directory:

export HTB_DOWNLOAD_DIR="D:/Sources/htb-app-mcp/downloads"

Environment variables

| Variable | Default | Usage | |---|---|---:|---| | HTB_API_TOKEN | empty | HTB token for stdio or HTTP fallback | | API_TOKEN | empty | Supported alias for compatibility | | HTB_TOKEN | empty | Supported alias | | HTB_API_BASE_URL | https://labs.hackthebox.com/api/v4 | Override base API URL | | HTB_DOWNLOAD_DIR | downloads | Download directory | | HTB_TIMEOUT | 30 | HTTP timeout to HTB in seconds | | HTB_LOAD_DOTENV | 1 | Set to 0 to disable .env loading | | HTB_MCP_TRANSPORT | stdio | stdio, http, streamable-http | | HTB_MCP_HOST | 127.0.0.1 | HTTP bind address | | HTB_MCP_PORT | 8000 | HTTP port | | HTB_MCP_PATH | /mcp | MCP HTTP path | | HTB_MCP_STATELESS_HTTP | 1 in HTTP mode | HTTP stateless by default | | HTB_MCP_JSON_RESPONSE | 0 | Return JSON responses where supported | | HTB_MCP_LOG_LEVEL | INFO | Server log level | | HTB_MCP_VERBOSE_HTTP | 0 | Set to 1 to re-enable verbose HTTPX logging | | HTB_DOWNLOAD_MIN_INTERVAL | 1.0 | Minimum seconds between ZIP downloads | | HTB_MCP_GRACEFUL_SHUTDOWN_TIMEOUT | 5 | Graceful shutdown timeout in seconds | | HTB_MCP_WINDOWS_SELECTOR_EVENT_LOOP | 1 | Use selector event loop on Windows |

CLI

uv run htb-app-mcp --help

Main options:

--transport {stdio,http,streamable-http}
--host 127.0.0.1
--port 8000
--path /mcp
--stateless-http
--stateful-http
--json-response
--log-level INFO
--graceful-shutdown-timeout 5

Local validation

Smoke test with direct client:

uv run python tests/smoke_client.py

Smoke test with MCP stdio:

uv run python tests/smoke_mcp.py

Smoke test with MCP HTTP and Authorization header:

uv run python tests/smoke_http.py

Troubleshooting

Session not found

Update the code and restart in default HTTP stateless mode:

uv run htb-app-mcp --transport http --host 127.0.0.1 --port 8000

If the client still holds an old connection, use reload MCP servers on the client side.

404 Not Found on /mcp

Check that:

• the server is started with --transport http

• the MCP config points to http://127.0.0.1:8000/mcp

• HTB_MCP_PATH or --path is not set to something other than /mcp

ConnectionResetError [WinError 10054] on Windows

The HTTP transport forces the selector event loop on Windows to avoid noisy stack traces when an MCP client closes a completed HTTP/SSE connection.

Traceback or ASGI callable returned without completing response on Ctrl+C

Shutdown handling is cross-platform: on Linux/macOS it uses standard Uvicorn signal handling; on Windows it enables the selector event loop only to avoid Proactor-specific noise. In all cases the server filters benign noise from Uvicorn/Starlette when closing HTTP MCP streams with Ctrl+C. For full debug logs, set HTB_MCP_VERBOSE_HTTP=1.

422 Unprocessable Entity

HTB rejects invalid parameters. The server normalizes common cases:

• Easy -> easy

• Very Easy -> very-easy

• unsolved -> incompleted

• solved -> complete

• sort_by=difficulty -> user_difficulty for challenges

• target_type=challenge -> challenges for search

If HTB changes the schema, use htb_api_get to test a read-only endpoint.

403 Forbidden during download

This is not necessarily a bug: HTB may deny access to challenges or files not available for your account plan, tier, status, or permissions.

429 Too Many Requests

You hit the HTB rate limit. The server serializes ZIP downloads, but if an agent requests many consecutive downloads, wait a few minutes or increase:

export HTB_DOWNLOAD_MIN_INTERVAL=2.0

Logs with signed URLs

HTTPX and httpcore logs are silenced by default to avoid printing temporary S3 URLs. For debugging:

export HTB_MCP_VERBOSE_HTTP=1

Do not share verbose logs: they may contain temporary presigned URLs.

Security

• Keep the HTTP server on loopback (127.0.0.1).

• Do not commit .env or tokens.

• Do not paste tokens in logs or the README.

• Avoid HTB_MCP_VERBOSE_HTTP=1 outside local debugging.

• Tools like spawn, stop, reset, submit flag, switch VPN have side effects on your HTB account.

API notes

HTB App v4 APIs are not officially stable for external integrations. Most public references are community-maintained or reverse-engineered; HTB may change paths, payloads, or permissions without notice.