Jexactyl is a customisable game management panel and billing system. From 4.0.0 until 4.0.5, the POST /api/client/billing/free/process endpoint accepts a client-controlled server_id and loads the server without restricting the lookup to servers owned by the authenticated account. On installations with billing enabled, an authenticated user can renew or unsuspend another tenant's billable server when its renewal_date is non-null and more than seven days away, even without a subuser relationship to that server. This issue is fixed in version 4.0.5.