Ledger finds flaw in Trezor Safe 7 chip; Trezor says user funds are safe

Ledger's Donjon security research team has disclosed a hardware vulnerability in the TROPIC01 chip used inside the Trezor Safe 7, demonstrating a lab-based laser attack that bypassed the chip's firmware verification system — though Trezor says no user funds are at risk. The attack, disclosed by both Ledger and chip maker Tropic Square, required decapsulating the chip and using a precisely calibrated 1064 nm laser to inject faults into the chip's signature verification process during firmware updates and device boot. In plain terms, a sufficiently equipped attacker with physical possession of a device could load unauthorized firmware onto the chip and, with additional fault injection during boot, execute it. Ledger's team confirmed successful execution by modifying the chip to return "HACK" in its basic device identification response — a flex as subtle as a brick through a window. The vulnerability affects all production TROPIC01 chips currently in the field, Tropic Square said.

Limited risk However, the practical danger has hard limits. The TROPIC01 chip is one of three independent security layers inside the Trezor Safe 7. User funds, wallet backups, and private keys are not stored on it, according to Trezor. The chip's hardware-backed secret storage — a mechanism called MAC-and-Destroy that underpins PIN verification — also resisted Ledger's extraction attempts entirely during their initial testing window, the team said. However, Tropic Square then conducted its own follow-up analysis and identified a separate attack path that could compromise that same MAC-and-Destroy boundary, going beyond what Ledger had found. It disclosed the existence of that additional vulnerability but is withholding technical details until a hardened silicon revision of TROPIC01 is available, currently scheduled for late 2026. Full details are expected to be published in spring 2027.

Still, an immediate firmware-based mitigation is available. It's possible to disable MAINTENANCE mode on the chip, which closes the attack's primary entry point and forces a more complex, multi-step exploit. The irony of disabling maintenance to improve security is not lost on anyone. Ledger Donjon said Tropic Square's engagement throughout the coordinated disclosure process was "exemplary," with the chip maker acknowledging findings promptly and moving quickly toward remediation.

Trezor's feedback Trezor said it informed all partners in advance and that no action is required from users. Trezor CEO Matej Zak stated that the disclosure is an outcome the company's design philosophy was built to produce. "The PIN, the wallet backup, and the keys to users' funds are never held on a single chip. That is by design," he said in a statement. "I believe the open process by which this vulnerability was found, examined, and disclosed is the model the industry should hold itself to." The disclosure continues a pattern of Ledger's Donjon security team surfacing hardware flaws in rival devices and vice versa. In March 2025, Trezor disclosed a vulnerability in its older Safe 3 model after Ledger researchers identified it, also describing the issue as largely theoretical and requiring physical access. Two hardware wallet labs, politely taking turns poking holes in each other's silicon — a healthier hobby than most.

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