A reflected cross-site scripting (XSS) vulnerability exists in the account registration flow of WSO2 Identity Server due to improper output encoding. A malicious actor can exploit this vulnerability by injecting a crafted payload that is reflected in the server response, enabling the execution of arbitrary JavaScript in the victim's browser. This vulnerability could allow attackers to redirect users to malicious websites, modify the user interface, or exfiltrate data from the browser. However, session-related sensitive cookies are protected using the httpOnly flag, which mitigates the risk of session hijacking.