What is a primary risk associated with cross-site scripting?

The primary risk associated with cross-site scripting (XSS) is the execution of malicious JavaScript. XSS vulnerabilities allow attackers to inject scripts into web pages viewed by other users. When a victim loads a webpage that has been tampered with, the malicious JavaScript can execute in the context of the user's browser. This can lead to several harmful consequences, including stealing session cookies, redirecting users to malicious sites, or performing actions on behalf of the user without their consent.

Understanding that XSS revolves around the execution of unauthorized scripts highlights the critical need for web developers to implement proper input validation and output encoding techniques to mitigate these types of attacks. By doing so, they can prevent the injection of malicious scripts and protect users from potential sessions hijacking and other related attacks.