InvoiceNinja v5-stable renders an invoice or quote's "terms" field in the client portal using Laravel Blade's raw output directive {!! $entity->terms !!} (resources/views/portal/ninja2020/invoices/includes/terms.blade.php) with no HTML sanitization. StoreInvoiceRequest.php only strips newlines from the field and does not purify HTML. An authenticated user with invoice creation access can set the terms field via the REST API (PUT /api/v1/invoices/{id}) to an HTML/JavaScript payload that executes in the client's browser when they view the invoice, enabling session cookie theft and client account takeover. This is a distinct code path from the previously published invoice line-item description field XSS (GHSA-98wm-cxpw-847p / CVE-2026-33628).