Cross-site scripting (XSS) is a prevalent security vulnerability that allows attackers to inject malicious scripts into web pages viewed by users, compromising user data such as cookies, session IDs, and private messages. This vulnerability ranks high on the OWASP Top 10 and is frequently reported on the Detectify Crowdsource platform. A notable example of an XSS attack was the Tweetdeck XSS worm in 2014, which spread through Twitter, compromising numerous accounts. XSS attacks often involve injecting scripts via user input fields, such as search boxes, which, if not properly validated, can lead to unauthorized data access and privilege escalation. Remediation strategies include converting user input to HTML entities, URL encoding, and using safe functions like innerText instead of innerHTML to prevent script execution. Detectify offers a web security scanner that automatically tests for XSS among over 1000 other vulnerabilities, providing a comprehensive solution for identifying and mitigating security risks on websites.