What Did Ledger Donjon Disclose?
Ledger Donjon researchers disclosed a security vulnerability in Tangem hardware wallet cards that can allow an attacker to reset a card’s password through a laser fault injection attack.
The attack targets Tangem firmware running on an EAL6+ secure element. According to the researchers, the fault injection bypasses a firmware check that verifies whether a card is in an authorized recovery state. Once that check is bypassed, the SetPin instruction can accept a new password without requiring the existing password or a backup card.
The finding matters because Tangem cards do not have a firmware update mechanism. Ledger Donjon said the vulnerability affects all Tangem cards currently in circulation and cannot be patched through a software update.
The exploit is not remote. It requires physical possession of the Tangem card, specialized laser fault-injection equipment, side-channel analysis tools, and hardware security expertise. Ledger Donjon said its lab setup cost about $250,000.
How Does the Attack Work?
The researchers said they prepared the card by exposing the secure element and connecting it to custom hardware. They then used a nanosecond laser pulse to target a specific area of the chip.
The laser fault injection caused the firmware to skip or bypass the recovery-state validation that should protect password changes. Once that happened, the attacker could set a new password on the card without knowing the original password.
After the password is reset, the attacker can use the card to sign transactions. That means funds associated with the wallet could be moved if the attacker has successfully compromised the card.
Ledger Donjon said it reproduced the attack on a second and third Tangem card after the initial demonstration. Each reproduction required about 2 hours of preparation and exploitation time.
Investor Takeaway
The vulnerability is serious at the hardware-security level, but its practical risk depends on physical access. For users and custodial service providers, the key exposure is lost, stolen, or unattended wallet cards rather than remote compromise.
What Are the Practical Risks for Users?
The attack is invasive and requires laboratory equipment, which limits its relevance for ordinary day-to-day use. It cannot be carried out through phishing, malware, a compromised phone, or a remote network attack. The attacker must have the physical card and enough time to perform chip-level work.
Ledger Donjon emphasized that point in its disclosure. “What this means for users: there’s no patch, but the attack is physical and invasive so it can’t be done covertly and the card returned intact,” the researchers wrote. “The only real risk is a lost or stolen card; if yours stays in your possession, the attack described here cannot be performed.”
That distinction is important for hardware wallet risk assessment. A non-patchable vulnerability creates a long-term concern for the product line, but the barrier to exploitation remains high. The most direct user response is operational: keep the card physically secure, treat a lost card as compromised, and move funds if the card leaves the owner’s control.
The finding also shows that secure element certification does not remove all firmware risk. Ledger Donjon said EAL6+ certification alone does not prevent fault injection attacks if firmware contains exploitable logic flaws.
How Did Tangem Respond?
Tangem disputed the practical significance of the findings. The company said the attack requires expensive laboratory equipment, physical possession of the card, and specialized expertise, making the risk to everyday users “virtually non-existent.”
Tangem also pointed to Ledger Donjon’s corporate affiliation. “It’s also worth noting that while Ledger Donjon presents itself as an independent research unit, it operates within Ledger, one of our largest competitors. Their findings should be read with that in mind,” the firm said. “Given enough time, funding and access, the firmware on any secure element can eventually be reverse-engineered and exploited.”
The response does not directly remove the technical issue, but it frames the vulnerability as a low-probability physical attack rather than a consumer-level security emergency. For Tangem, the core challenge is that the cards cannot be patched, leaving the company to rely on risk communication, future product changes, and user guidance rather than a firmware fix.
Ledger Donjon said it had previously found a genuine check bypass in the Tangem Android application and a brute-force attack against the card’s authentication protocol. The latest vulnerability was disclosed to Tangem in February.
What Does This Mean for Hardware Wallet Security?
The Tangem disclosure highlights a broader issue for hardware wallet makers: physical attacks may be rare, but they remain important because hardware wallets are designed to protect high-value assets under hostile conditions.
Wallet vendors must balance usability, recoverability, secure element design, and firmware validation. Recovery functions are especially sensitive because they are meant to restore access without weakening the protections that prevent unauthorized password changes.
Ledger Donjon recommended that secure element firmware use multiple independent checks for sensitive operations, strengthen state validation methods, and keep password changes protected when recovery features are disabled.
For investors, exchanges, custodians, and long-term holders, the lesson is practical. Hardware wallets reduce many online risks, but they do not eliminate physical custody risk. Devices that cannot be updated may require stricter handling policies, especially when they secure material balances or institutional funds.
