When a cookie is protected with the secure attribute set to true it will not be send by the browser over an unencrypted HTTP request and thus cannot be observed by an unauthorized person during a man-in-the-middle attack.

Ask Yourself Whether

There is a risk if you answered yes to any of those questions.

Recommended Secure Coding Practices

Sensitive Code Example

Using Flask:

from flask import Response

@app.route('/')
def index():
    response = Response()
    response.set_cookie('key', 'value')  # Sensitive
    return response

Using FastAPI:

from fastapi import FastAPI, Response

app = FastAPI()

@app.get('/')
async def index(response: Response):
    response.set_cookie('key', 'value')  # Sensitive
    return {"message": "Hello world!"}

Compliant Solution

Using Flask:

from flask import Response

@app.route('/')
def index():
    response = Response()
    response.set_cookie('key', 'value', secure=True)
    return response

Using FastAPI:

from fastapi import FastAPI, Response

app = FastAPI()

@app.get('/')
async def index(response: Response):
    response.set_cookie('key', 'value', secure=True)
    return {"message": "Hello world!"}

See