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.
Remediation
Apply context-dependent encoding and/or validation to user input rendered on a page
References
Cross-site Scripting (XSS) Attack - Acunetix
XSS Filter Evasion Cheat Sheet
Excess XSS, a comprehensive tutorial on cross-site scripting
Related Vulnerabilities
Drupal Core 9.1.x Cross-Site Scripting (9.1.0 - 9.1.6)
WordPress Plugin Vospari Forms Cross-Site Scripting (1.3)
Joomla! Core 3.x.x Cross-Site Scripting (3.0.0 - 3.2.2)
WordPress Plugin PickPlugins Product Slider for WooCommerce Cross-Site Scripting (1.13.21)
WordPress Plugin Appointment Hour Booking-WordPress Booking Cross-Site Scripting (1.3.15)