Which statement is false in reference to XSS attacks?

The statement that XSS attacks cannot be performed through emails or mail clients is indeed inaccurate. Cross-site scripting (XSS) attacks involve the injection of malicious scripts into web pages, which can lead to the execution of these scripts in the context of a user's browser. While XSS is primarily associated with web applications, it is important to note that emails can also serve as a vector for XSS attacks, particularly through HTML emails.

In an HTML email, an attacker could include JavaScript or other executable content that, when opened by the recipient, executes the malicious script. This can compromise the security of client-side applications if the email is opened in a vulnerable client, leading to unauthorized actions or data exposure.

Other statements correctly encapsulate the nature of XSS attacks. They highlight that these attacks are fundamentally about injecting scripts into web applications and compromising client-side security, reflecting the serious implications of such vulnerabilities.