PYSEC-2026-471

### Summary

The `--mcp` CLI argument is passed directly to `shlex.split()` and forwarded through the call chain to `anyio.open_process()` with no validation, allowlist check, or sanitization at any hop, allowing arbitrary OS command execution as the process user.

### Details

`cli/features/mcp.py:61` (source) -> `praisonaiagents/mcp/mcp.py:345` (hop) -> `mcp/client/stdio/__init__.py:253` (sink) ```python # source parts = shlex.split(command)

# hop cmd, args, env = self.parse_mcp_command(command, env_vars) self.server_params = StdioServerParameters(command=cmd, args=arguments) # sink process = await anyio.open_process([command, *args])

```

Fixed in commit `47bff65413beaa3c21bf633c1fae4e684348368c` (v4.5.69) by introducing a command allowlist: ```python ALLOWED_COMMANDS = {"npx", "uvx", "node", "python"} if cmd not in ALLOWED_COMMANDS: raise ValueError(f"Disallowed command: {cmd}") ```

### PoC ```python # tested on: praisonai==4.5.48 # install: pip install praisonai==4.5.48 # run: praisonai --mcp "bash -c 'id > /tmp/pwned'" # verify: cat /tmp/pwned # expected output: uid=1000(...) gid=1000(...) groups=1000(...) ```

### Impact

Any deployment where the `--mcp` argument is influenced by untrusted input is exposed to full OS command execution as the process user. No authentication is required.