An explanation from TurboTax would be nice. Who needs access to all devices on my network, why and is the access read only? The download process involves a communication chain that includes TurboTax, a browser, Intuit, a financial institution, and likely other intermediaries. Which of these needs to access all the devices on my network? I assume TurboTax understands the chain of exchanges that allows the download, and TurboTax probably believes strongly that this relaxation of security does not expose its customers to a risk. But that's almost always the case when vulnerabilities are created. Customers asked to disable security measures are entitled to an explanation in my humble opinion.
