The authentication endpoint generates an error message that includes reflected data directly from the request without sufficient sanitization or encoding. This allows an attacker to inject malicious scripts that can be executed in the context of a victim's browser.

Successful exploitation enables an attacker to perform actions within the user's browser, such as redirecting the user to a malicious website, modifying the web page's user interface, or retrieving information. However, due to the httpOnly flag on session-related cookies, session hijacking or similar attacks are not possible.