The Note Mark backend's GET /api/books/{bookID}/notes endpoint is unauthenticated and accepts a 'deleted' query parameter. When 'deleted=true', the query uses an unscoped database call that bypasses the soft-delete filter but retains an authorization clause allowing access if the book is public or owned by the requester. Because the endpoint lacks authentication, unauthenticated users can enumerate metadata of soft-deleted notes on public books. The note content endpoint does not expose soft-deleted notes, limiting impact to metadata disclosure. The root cause is improper authorization logic that does not restrict soft-deleted notes to owners only. The recommended fix is to modify the authorization check so that when 'deleted=true', only the owner can access the notes, effectively blocking unauthenticated access to trashed notes.

Exposure of metadata (id, title, slug, timestamps) for soft-deleted notes on public books to unauthenticated actors. The note content remains protected and inaccessible for soft-deleted notes. This bypasses the intended semantics of deletion, potentially revealing information the owner expected to be hidden. There is no impact on note integrity or availability, only metadata confidentiality is affected.

No official patch or fix is currently published. Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. The recommended code change is to restrict soft-deleted note listings to the book owner only, removing the 'is_public' condition when 'deleted=true'. This prevents unauthenticated users from accessing trashed note metadata. Until a fix is released, avoid exposing soft-deleted notes via unauthenticated endpoints or implement access controls restricting this data to authenticated owners.