Bitwarden Server before 2026.5.0 contains a broken access control vulnerability that allows any authenticated user to access arbitrary organization billing data by supplying an arbitrary organizationId to the PreviewInvoiceController endpoints without membership or authorization checks. Attackers can exploit the missing ManageOrganizationBillingRequirement on the preview invoice endpoints to retrieve Stripe-computed tax totals, subscription status, and billing details derived from any target organization's real customer and subscription data.