Attach API

The attach sidecar API is a local FastAPI service started in HTTP mode. It provides a simple wrapper for process-attach workflows.

The attach sidecar is separate from the main MCP endpoint and is not started in stdio mode.

Default endpoint

POST http://127.0.0.1:5501/attach

Request body

{
  "pre": ["set pagination off"],
  "pid": 31337,
  "after": ["info threads"],
  "where": "/workspace/chal",
  "session_id": "chal-a"
}

Request fields

number

required

Target process id to attach to.

string

required

Target debug session id. The session must already exist.

string

Optional binary path to load before attach. Use a path that resolves under /workspace.

string[]

Optional GDB or pwndbg commands executed before the attach.

string[]

Optional GDB or pwndbg commands executed after a successful attach.

Response shape

{
  "successful": true,
  "attach": {
    "command": "attach",
    "success": true,
    "state": "stopped",
    "pid": 31337,
    "session_id": "chal-a"
  },
  "result": {
    "set-file": {
      "success": true
    },
    "info threads": {
      "success": true
    }
  }
}

Response fields

boolean

required

Whether the overall attach request succeeded.

object

Structured summary of the attach attempt.

Show properties

string

Command label associated with the attach action.

boolean

Whether the attach itself succeeded.

string

Current debugger or inferior state after the attach.

number

Attached process id.

string

Debug session used for the request.

string

Present when attach setup or attach execution fails.

object

required

Map of pre-commands, optional set-file, and post-commands to their individual command results.

Python helper

pwnomcp.cli.attach() wraps the same API.

from pwnomcp.cli import attach

response = attach(
    pid=31337,
    session_id="chal-a",
    gdbscript=["set pagination off"],
    artifact_path="/workspace/chal",
)

print(response.model_dump())

When to use it

use the MCP attach tool for normal in-client workflows
use /attach or pwnomcp.cli.attach() when you already have a local Python helper or external integration that wants a small HTTP contract

Debugger and Inspection

Automation and Exploit I/O

Default endpoint

Request body

Request fields

Response shape

Response fields

Python helper

When to use it

​Default endpoint

​Request body

​Request fields

​Response shape

​Response fields

​Python helper

​When to use it

Default endpoint

Request body

Request fields

Response shape

Response fields

Python helper

When to use it