✍️ Description

Cross-site Scripting (XSS) refers to client-side code injection attack wherein an attacker can execute malicious scripts into a legitimate website or web application. XSS occurs when a web application makes use of unvalidated or unencoded user input within the output it generates.

The user input GET parameter username of pg_users.php is unsanitized resulting reflected cross site scripting.

Remediation

Apply context-dependent encoding and/or validation to user input rendered on a page