Discord WebSocket API service vulnerabilities

Discord through 2026-01-16 allows gathering information about whether a user's client state is Invisible (and not actually offline) because the response to a WebSocket API request includes the user in the presences array (with "status": "offline"), whereas offline users are omitted from the presences array. This is arguably inconsistent with the UI description of Invisible as "You will appear offline." NOTE: a third-party report suggests that this was remediated later in 2026.