An administrator discovers a cross-site scripting vulnerability on a company website. Which of the following will most likely remediate the issue?

Input validation is an essential security practice that ensures data received by the application meets specific criteria. While it can help mitigate XSS by rejecting harmful input, it may not cover all attack vectors and is often not sufficient alone. Therefore, it serves as a preventative measure but does not provide the comprehensive protection that a WAF can offer.

Next-Generation Firewalls (NGFW) provide advanced network security features, including application awareness and control, but they primarily focus on network-level threats. While they can inspect traffic, they are not specifically designed to handle web application vulnerabilities such as XSS, making them less effective for this particular issue.

A vulnerability scan identifies potential security weaknesses in systems and applications, but it does not actively remediate any vulnerabilities discovered. While conducting scans is an important part of a security strategy, it merely highlights issues without providing a means for immediate protection against XSS attacks.