Advisories for Golang/Github.com/Enchant97/Note-Mark/Backend package

A timing side-channel in the login endpoint allows unauthenticated attackers to determine whether a username exists by measuring response time differences. Requests for valid usernames take noticeably longer because the server performs bcrypt password verification, while requests for nonexistent usernames return much faster. This enables reliable remote username enumeration and increases the risk of targeted credential attacks.

A stored same-origin XSS vulnerability allows any authenticated user to upload an HTML, SVG, or XHTML file as a note asset and have it executed in a victim’s browser under the application’s origin. Because the application serves these files inline without a safe content type and without nosniff, browsers can sniff and render active content, giving the attacker access to authenticated Note Mark API actions as the victim.

A broken access control vulnerability allows unauthenticated users to retrieve note assets directly from the asset download endpoint when they know both the note UUID and asset UUID. This exposes the full contents of private note assets without authentication, even when the associated book is not public.