BootROM vulnerability and Seed Phrase Storage Warning for iPhone 11 and Earlier

OneKey co-founder Yishi warned on October 31 via X that iPhones 11 and older should not be used to store crypto wallet seed phrases, citing two boot-stage chip vulnerabilities that cannot be fixed through iOS updates. The warning centers on the checkm8 exploit, which per US CERT/CC affects devices running Apple's A5 through A11 chips—spanning the iPhone 4S through iPhone X—with exploitation requiring physical possession of the device, connection to a computer, and entry into Device Firmware Update (DFU) mode. The advisory matters because seed phrases stored on affected hardware could be extracted by attackers with physical access, and the chip-level nature of the flaw means no software patch can remediate it. Yishi framed the statement as a storage recommendation rather than a confirmed breach, noting the actual vulnerability scope varies by chip generation. Users self-custodying crypto on older iPhones should migrate seed phrases to dedicated hardware wallets or newer devices. Watch for further clarification from Apple or security researchers on per-chip-generation exposure and whether exploitation is observed in the wild.