It's basically the worst security bug in the history of security bugs.
If you are using a Mac running 10.7 or later, an iPhone 4 or later, or an iPad 2 or later, you have to upgrade your OS, right now.
If, like me, you've been putting off upgrading from iOS 6 to iOS 7, bummer. You don't have a choice now.
Here's a site that may test whether you're vulnerable.
Jeff Weinstein said, "Thanks, Apple, for making the Netscape Random Number Seed bug look minor."
Someone else said, "If you want a tour of of the Oval Office, just write 'Mr. President' on your t-shirt. They probably haven't upgraded yet."
It's egregious enough that enemy action isn't entirely out of the question.