What is XSS and how can I prevent it in my Python web applications?

What is XSS and how can I prevent it in my Python web applications?

XSS, or Cross-Site Scripting, is a security vulnerability that allows attackers to inject malicious scripts into web pages viewed by users. To prevent XSS in Python web applications, you can use input validation, output encoding, and libraries like Flask-WTF for form handling.

Can you give me an example of how to implement output encoding?

Sure! In a Flask application, you can use the escape function from the markupsafe library to encode user input before rendering it in templates. For example: from markupsafe import escape; safe_input = escape(user_input).

What are some common libraries to help prevent XSS?

Some common libraries include Flask-WTF for form handling, Bleach for sanitizing HTML, and Django's built-in template system which auto-escapes variables.

How can I test my application for XSS vulnerabilities?

You can use tools like OWASP ZAP or Burp Suite to scan your application for XSS vulnerabilities. Additionally, manual testing by trying to inject scripts can help identify weaknesses.