The authentication endpoint does not properly encode user-supplied input before rendering it within the web page. This lack of output encoding allows an attacker to inject malicious JavaScript payloads into the authentication flow, which are then executed by the victim's browser. By exploiting this vulnerability, an attacker can redirect the user's browser to a malicious website, modify the content of the web page displayed to the user, or exfiltrate information from the browser. However, due to the implementation of the httpOnly flag on session-related sensitive cookies, session hijacking and similar attacks are not possible.