Patched code sample

import functools
from flask import Flask, request, abort

# This example uses the Flask framework to simulate Tautulli's web server.
app = Flask(__name__)

# A mock database representing the 'image_hash_lookup' table.
# A low-privilege user has already "seeded" a malicious URL.
IMAGE_HASH_LOOKUP = {
    'd34db33f': 'http://legitimate.image.host/image.png',
    # Malicious entry for SSRF, pointing to internal cloud metadata service
    'a1b2c3d4': 'http://169.254.169.254/latest/meta-data/'
}

# --- The Fix ---
# The vulnerability was that the /image/<hash> endpoint was unauthenticated.
# The fix is to enforce authentication on this endpoint, preventing an
# unauthenticated attacker from triggering the server-side request.
# This is represented by the `login_required` decorator.

def login_required(f):
    """A simple decorator to simulate checking for user authentication."""
    @functools.wraps(f)
    def decorated_function(*args, **kwargs):
        # In a real application, this would inspect a session cookie or auth header.
        # For this example, we'll just check for a 'token' in the request headers.
        # If the token is missing, it returns a 401 Unauthorized error.
        if 'token' not in request.headers:
            abort(401, description="Authentication required.")
        # If authenticated, proceed to the original function.
        return f(*args, **kwargs)
    return decorated_function

# The vulnerable endpoint was public. The fixed endpoint is now protected
# by the `login_required` decorator.
@app.route('/image/<image_hash>')
@login_required  # <-- THIS DECORATOR IS THE FIX
def get_image_by_hash(image_hash):
    """
    Fetches an image using a hash. Access is now restricted to authenticated
    users, preventing the unauthenticated SSRF vulnerability.
    """
    image_url = IMAGE_HASH_LOOKUP.get(image_hash)

    if not image_url:
        abort(404, description="Image hash not found.")

    # The server-side request would happen here.
    # By requiring authentication first, we prevent an unauthenticated
    # attacker from triggering this fetch logic. The SSRF primitive is
    # now only accessible to authenticated users, matching the behavior
    # of other authenticated image proxying features.
    print(f"Authenticated user triggered fetch for URL: {image_url}")

    # In a real app, the server would fetch the URL and return the image data.
    return f"Authenticated fetch for {image_url} would now proceed.", 200