OnKey Founder Warns Users Against Storing Seed Phrases on Older iPhones

OnKey founder Yishi warned crypto users against keeping wallet recovery phrases on iPhone 11 and older models, citing boot-level vulnerabilities that iOS updates cannot fix.

Yishi’s warning covers two vulnerability groups. The checkm8 flaw affects the BootROM in iPhone 4S through iPhone X. The usbliter8 vulnerability, disclosed in June 2026, affects iPhone XS, XR and 11 series, as well as the second-generation iPhone SE.

Yishi said an attacker with physical access could connect a phone by USB and run code before iOS starts. Airplane mode would not prevent the attack.

For users who stored recovery phrases on affected devices, Yishi advised creating new phrases in a trusted environment and moving their assets. Generating another wallet address from the existing phrase would not address the risk, Yishi said.

Yishi also recommended updating device software, using stronger device and wallet passwords, avoiding public USB charging ports and staying alert to physical-attack risks when a device has been out of its owner’s control for an extended period.