New Unpatchable BootROM Exploit Targets Apple’s A12 and A13 Chips

By NewSunSEO | July 14, 2026

A security research firm has published details of an unpatchable BootROM vulnerability in Apple’s A12 and A13 chips, along with a working proof-of-concept exploit called “usbliter8.” Because the flaw is built into the chip at manufacture, no iOS update can fix it, leaving affected devices permanently exposed. The vulnerability targets devices from the iPhone XS through the iPhone 11 series.

What Is the BootROM and Why Can’t Apple Patch It?

The BootROM, also known as SecureROM, is the first code an iPhone runs when it powers on. Once a vulnerability is found at this level, no iOS update can patch it, because Apple cannot rewrite the contents of the chip after production. The last publicly known BootROM exploit of this kind was "checkm8," released in 2019, which affected devices from the iPhone 4S through the iPhone X. With usbliter8, the lineage extends to the next generation of Apple silicon.

How Does the Exploit Work?

The exploit targets a bug in the USB controller built into Apple’s chips. When an iPhone receives USB traffic during startup, the controller uses a memory buffer to store incoming packets. The researchers found that by sending a specific sequence of unusually small packets, they could manipulate an internal hardware pointer so that it walks backward through memory, allowing data to be written to locations it should not reach. The researchers note that this appears to be a flaw in the USB controller hardware, not in Apple’s software.

The A11, used in the iPhone X, is not affected because its USB driver manually resets the pointer after each packet. A14 and newer chips are also safe, since they correctly configure a memory protection feature at the BootROM level. The A12 and A13 sit in a vulnerable middle ground between the two.

Why Are A12 and A13 Different to Exploit?

On A12 devices, gaining code execution is relatively straightforward. On A13 devices, Apple had introduced Pointer Authentication Codes (PAC), a security feature designed to detect and block certain types of memory tampering. Working around PAC on the A13 required a multi-step process before the researchers could take control of the processor.

What Can an Attacker Do With It?

After taking control, the exploit installs a custom handler that survives a device restart and adds two capabilities: temporarily lowering the device’s security settings, and booting unsigned software without any verification checks. As a marker of compromise, it also injects the traditional "PWND" string into the iPhone’s USB serial number, a convention carried over from checkm8 and earlier exploits.

Does It Affect the Secure Enclave?

Security researchers note that usbliter8 does not directly affect the Secure Enclave, but a BootROM compromise of this kind opens wider avenues for attacking it. The firm reports that it shared its findings with Apple Product Security before publication and coordinated disclosure with Apple. The proof-of-concept code is at ps.tc.

FAQ

Which iPhones are affected by the usbliter8 BootROM exploit?

The exploit affects devices using Apple’s A12 and A13 chips, covering the iPhone XS through the iPhone 11 series. The iPhone X (A11) and A14 or newer devices are not affected.

Why can’t Apple fix this with an iOS update?

The vulnerability lives in the BootROM, the first code the iPhone runs when it powers on, which is baked into the chip at manufacture. Apple cannot rewrite the contents of the chip after production, so no iOS update can patch the flaw.

Was Apple notified before the exploit was published?

Yes. Reports that it shared its findings with Apple Product Security before publication and coordinated disclosure with Apple.