Ledger Reveals Unpatchable Security Flaw in MediaTek Smartphone Chip, Threatening Crypto Wallets

Crypto hardware wallet provider Ledger has disclosed a critical, unpatchable vulnerability in a widely used smartphone chip from MediaTek. The flaw, found in the MediaTek Dimensity 7300 (MT6878) system-on-chip (SoC), allows attackers to gain complete and absolute control over a device through a physical electromagnetic fault injection (EMFI) attack.

Ledger's security research team, Donjon, detailed in a report published on Wednesday that by applying precisely timed electromagnetic pulses during the chip's initial boot process, they could bypass all security measures and escalate to the highest privilege level (EL3) in the ARM architecture. This grants an attacker the ability to extract private keys stored on the device, directly threatening the security of cryptocurrency wallets held on smartphones.

The vulnerability is located in the chip's boot ROM (Read-Only Memory), which is coded into the silicon during manufacturing. This means the flaw cannot be fixed via a software update or patch, leaving all devices using this chip permanently vulnerable. MediaTek, in a statement included in Ledger's report, acknowledged that electromagnetic fault injection attacks are "out of scope" for the MT6878, as it is a consumer-grade component not designed for high-security financial applications like hardware security modules (HSMs).

While the success rate of a single attack attempt is low—between 0.1% and 1%—the process can be repeated every second. Ledger researchers Charles Christen and Léo Benito stated that this allows an attacker to gain full access in "only a matter of a few minutes" under lab conditions. They began the experiment in February and successfully exploited the chip in early May, promptly disclosing the findings to MediaTek's security team.

The report underscores a growing threat vector for cryptocurrency users who rely on smartphone-based "hot" wallets for self-custody. Ledger emphasized that secure-element chips, like those used in its hardware wallets, are specifically designed to withstand such physical attacks and remain necessary for safeguarding private keys. The findings were published amid a surge in crypto-related thefts, with over $2.17 billion stolen from services in 2025 alone according to a July Chainalysis report.