ITFlow provides an IT documentation, ticketing and accounting system for small managed service providers. Prior to version 26.07, an authenticated Technician or higher with access to at least one client invoice can inject SQL through the frequency parameter handled by agent/post/recurring_invoice.php. The handler passes recurring_invoice_frequency through sanitizeInput but interpolates it unquoted into DATE_ADD, allowing SQL syntax to escape the interval expression, assign additional INSERT columns, store subquery results in recurring_invoice_note, and expose those results through agent/recurring_invoice.php. The persisted recurring_invoice_frequency can execute again when Force Recurring uses it in a later UPDATE, allowing another legitimate user to trigger the second-order injection. This can expose password hashes, SMTP credentials, user records, and database metadata, modify database fields, and enable administrative takeover after credential cracking. This issue is fixed in version 26.07.