Inspect one CORS response

Before you begin

• Python 3.12 or later.
• A reachable endpoint you administer supporting HEAD.

Set up your example

1. Save as security-cors-response.py.
2. Open a terminal in its folder.
3. Run python "security-cors-response.py" --help and prepare the listed input files.

This recipe uses your own local input or creates its own example output. Follow the setup steps below.

Download the ZIP, extract it, and open a terminal inside the extracted folder. The source file is security-cors-response.py.

Run the script

python "security-cors-response.py" "http://127.0.0.1:8000/"

If your system uses python3 instead of python, use that command for Python examples. Keep paths containing spaces in quotes. Required inputs and optional settings are described in the code and setup steps.

What to expect

The complete script

#!/usr/bin/env python3
"""Send one HEAD request with a synthetic Origin and inspect CORS response declarations."""
import argparse
import sys
import json
from pathlib import Path
from urllib.request import Request,urlopen
from urllib.parse import urlsplit
from urllib.error import HTTPError

def head(url,extra=None):
    p=urlsplit(url)
    if p.scheme not in {'http','https'} or not p.hostname or p.username is not None or p.password is not None:raise ValueError('Use an HTTP(S) URL without credentials')
    request=Request(url,method='HEAD',headers={'User-Agent':'Scriptage-local-check/1.0',**(extra or {})})
    try:return urlopen(request,timeout=10)
    except HTTPError as response:return response

def main():
    parser = argparse.ArgumentParser(description='Send one HEAD request with a synthetic Origin and inspect CORS response declarations.')
    parser.add_argument('url')
    args = parser.parse_args()
    with head(args.url,{'Origin':'https://audit.invalid'}) as response:
        origin=response.headers.get('Access-Control-Allow-Origin')
        credentials=response.headers.get('Access-Control-Allow-Credentials','').lower()
        print(json.dumps({'status':response.status,'allow_origin':origin,'allow_credentials':credentials,'wildcard_with_credentials':origin=='*' and credentials=='true'},indent=2))

if __name__ == '__main__':
    try:
        main()
    except (OSError, ValueError, RuntimeError) as exc:
        print(f'Error: {exc}', file=sys.stderr)
        sys.exit(1)

Open source as plain text · Download source and sample files

How it works

1. Send one HEAD request with a synthetic Origin and inspect CORS response declarations.
2. Arguments are explicit and expected input errors produce a message with a nonzero exit code.
3. Results reflect your selected local data or the specific endpoint you choose; the example illustrates the result shape.

Make it your own

Adapt the task

Replace the synthetic Origin in the head call with an origin relevant to your authorized application test; this is not a preflight test.

Adjust presentation

Edit final print statements or json.dumps indentation to adjust the report layout. Keep input validation and exclusive-create file modes intact.

Change one setting at a time, run it again on sample data, and compare the output. The customization guide walks through this process.

If something goes wrong

Reference & next steps

• Python standard library documentation ↗

These official references explain the underlying tools. The Scriptage example and guide are original instructional content. See verification notes for what has been checked and the limits of those checks.

Copies a template for your own notes. It does not send anything.