Security researchers have found an unfixable BootROM vulnerability in Apple A12 and A13 chips, and the bad news is as blunt as it sounds: no iOS update can patch it. The flaw affects millions of older iPhones, including the iPhone XS, XS Max, XR, iPhone 11, 11 Pro, and 11 Pro Max, while newer Apple silicon has already moved past the problem.
The exploit, called ”usbliter8”, targets the very first code that runs when the device powers on. Because BootROM is baked into the chip at manufacture, Apple cannot simply push out a software fix after the fact. That puts it in the same unpleasant category as the long list of hardware-level bugs that keep security teams busy long after a product launch party has been forgotten.
How the Apple A12 and A13 BootROM flaw works
According to the researchers, the issue comes from a hardware mistake in the USB controller. By sending a specific sequence of USB packets, an attacker can write data into a memory region that should normally be off-limits. On A12 devices, the exploit is relatively straightforward; on A13, it required bypassing Pointer Authentication Codes, Apple’s extra layer of protection.
- Affected chips: Apple A12 and A13
- Affected devices: iPhone XS, iPhone XS Max, iPhone XR, iPhone 11, iPhone 11 Pro, iPhone 11 Pro Max
- Unchanged by the bug: A11 in iPhone X
- Already fixed in architecture: Apple A14 and newer
Why Apple cannot patch this one away
BootROM vulnerabilities are especially annoying because they sit below the operating system. That means iOS can add protections around them, but it cannot erase the underlying bug. Apple has dealt with similar hardware-era headaches before, and the usual pattern is the same: older devices live with the risk, while the company leans harder on architectural changes in newer chips.
The silver lining, such as it is, is that the problem stops at A13. A11 is spared thanks to a different USB-driver implementation, and A14 and later designs were built after Apple had already closed this class of weakness. For owners of the affected phones, though, the lesson is less cheerful: some security holes do not get an update, they get a retirement plan.
What iPhone owners should expect now
There is no indication that this flaw hits everyday users all at once, but any BootROM bug is valuable to attackers because it sits so deep in the stack. Expect Apple to rely on mitigations, not miracles, for these models. The bigger question is how long older iPhones stay attractive targets once a public exploit is circulating: long enough for some very nervous security teams, and probably long enough for Apple to keep telling people that newer hardware is the cleaner answer.