Updated warning about binding to non-local interfaces. (#1653)

Author: afourney

packages/markitdown-mcp/README.md

@@ -1,5 +1,9 @@
 # MarkItDown-MCP
 
+> [!IMPORTANT]
+> The MarkItDown-MCP package is meant for **local use**, with local trusted agents. In particular, when running the MCP server with Streamable HTTP or SSE, it binds to `localhost` by default, and is not exposed to other machines on the network or Internet. In this configuration, it is meant to be a direct alternative to the STDIO transport, which may be more convenient in some cases. DO NOT bind the server to other interfaces unless you understand the [security implications](#security-considerations) of doing so.
+
+
 [![PyPI](https://img.shields.io/pypi/v/markitdown-mcp.svg)](https://pypi.org/project/markitdown-mcp/)
 ![PyPI - Downloads](https://img.shields.io/pypi/dd/markitdown-mcp)
 [![Built by AutoGen Team](https://img.shields.io/badge/Built%20by-AutoGen%20Team-blue)](https://github.com/microsoft/autogen)
@@ -18,14 +22,14 @@ pip install markitdown-mcp
 
 ## Usage
 
-To run the MCP server, using STDIO (default) use the following command:
+To run the MCP server, using STDIO (default), use the following command:
 
 
 ```bash	
 markitdown-mcp
 ```
 
-To run the MCP server, using Streamable HTTP and SSE use the following command:
+To run the MCP server, using Streamable HTTP and SSE, use the following command:
 
 ```bash	
 markitdown-mcp --http --host 127.0.0.1 --port 3001
@@ -96,7 +100,7 @@ If you want to mount a directory, adjust it accordingly:
 
 ## Debugging
 
-To debug the MCP server you can use the `mcpinspector` tool.
+To debug the MCP server you can use the `MCP Inspector` tool.
 
 ```bash
 npx @modelcontextprotocol/inspector
@@ -127,7 +131,7 @@ Finally:
 
 ## Security Considerations
 
-The server does not support authentication, and runs with the privileges of the user running it. For this reason, when running in SSE or Streamable HTTP mode, it is recommended to run the server bound to `localhost` (default).
+The server does not support authentication, and runs with the privileges of the user running it. For this reason, when running in SSE or Streamable HTTP mode, the server binds by default to `localhost`. Even still, it is important to recognize that the server can be accessed by any process or users on the same local machine, and that the `convert_to_markdown` tool can be used to read any file that the server's user has access to, or any data from the network. If you require additional security, consider running the server in a sandboxed environment, such as a virtual machine or container, and ensure that the user permissions are properly configured to limit access to sensitive files and network segments. Above all, DO NOT bind the server to other interfaces (non-localhost) unless you understand the security implications of doing so.
 
 ## Trademarks
 

packages/markitdown-mcp/src/markitdown_mcp/__about__.py

@@ -1,4 +1,4 @@
 # SPDX-FileCopyrightText: 2024-present Adam Fourney <adamfo@microsoft.com>
 #
 # SPDX-License-Identifier: MIT
-__version__ = "0.0.1a4"
+__version__ = "0.0.1a5"

packages/markitdown-mcp/src/markitdown_mcp/__main__.py

@@ -113,10 +113,23 @@ def main():
         sys.exit(1)
 
     if use_http:
+        host = args.host if args.host else "127.0.0.1"
+        if args.host and args.host not in ("127.0.0.1", "localhost"):
+            print(
+                "\n"
+                "WARNING: The server is being bound to a non-localhost interface "
+                f"({host}).\n"
+                "This exposes the server to other machines on the network or Internet.\n"
+                "The server has NO authentication and runs with your user's privileges.\n"
+                "Any process or user that can reach this interface can read files and\n"
+                "fetch network resources accessible to this user.\n"
+                "Only proceed if you understand the security implications.\n",
+                file=sys.stderr,
+            )
         starlette_app = create_starlette_app(mcp_server, debug=True)
         uvicorn.run(
             starlette_app,
-            host=args.host if args.host else "127.0.0.1",
+            host=host,
             port=args.port if args.port else 3001,
         )
     else: