Data placed in the localStorage persists after a session is closed, and thus, any actor with access to the browser will be able to obtain it. Furthermore, data in the localStorage or in the sessionStorage is visible to scripts that are running on the browser, and these scripts could belong to malicious third parties. Therefore, no sensitive or session information should be stored in the client-side storage.

Increased risk of data breaches, financial loss, and reputational harm. Eroding customer trust and confidence.