In a statement issued by the company, “Old source code from three years ago appears to have been leaked, but by design the security of our products doesn’t depend on the secrecy of our source code. There are many layers of hardware and software protections built into our products, and we always encourage customers to update to the newest software releases to benefit from the latest protections.”
For those unfamiliar, the leak was that of iOS 9 and it was for iBoot which is the first process that runs whenever you turn on your iPhone. It is also what verifies that the software you run has been signed by Apple to ensure that unauthorized software isn’t being used on the phone. However given that only about 7% of iOS devices still run on iOS 9, any potential issues will probably only affect a small number of users at worst.