Certified Ethical Hacker (CEH) v13 312-50v13 — Question 239

An ethical hacker is testing a web application of a financial firm. During the test, a 'Contact Us' form's input field is found to lack proper user input validation, indicating a potential Cross-Site Scripting (XSS) vulnerability. However, the application has a stringent Content Security Policy (CSP) disallowing inline scripts and scripts from external domains but permitting scripts from its own domain. What would be the hacker's next step to confirm the XSS vulnerability?