I've already stated that Cross-site scripting is absurdly easy. Amusingly, it is slightly harder to perform stored Cross-site scripting in a scripted fashion. I should probably take back my earlier words at this point, but whatever. The difficulty here is that systems often take an input structure from one page, submit to another page, and return a third page. The following script is designed to handle that most complex of structures.

We will create a script that takes three input values, reads, and submits to all three correctly and checks for success. It shares code with the earlier URL-based Cross-site scripting but differs fundamentally in its execution.

import requests
import sys
from bs4 import BeautifulSoup, SoupStrainer
url = "http...