Ledger Donjon researchers disclosed a security vulnerability in Tangem hardware wallet cards that allows 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 and bypasses a firmware check verifying whether a card is in an authorized recovery state, enabling the SetPin instruction to accept a new password without requiring the existing password or backup card. The vulnerability was disclosed to Tangem in February and affects all Tangem cards currently in circulation because the cards lack a firmware update mechanism and cannot be patched through software updates. The exploit requires physical possession of the card, specialized laser fault-injection equipment costing approximately $250,000, side-channel analysis tools, and hardware security expertise, making it a physical rather than remote attack vector. This finding highlights ongoing challenges in hardware wallet security where secure element certification does not eliminate all firmware risks, particularly for devices without update capabilities.
Ledger Donjon Demonstrates Laser Fault Injection Attack on Tangem Cards
The researchers prepared the card by exposing the secure element and connecting it to custom hardware, 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, meaning funds associated with the wallet could be moved if the attacker has successfully compromised the card. Ledger Donjon reproduced the attack on a second and third Tangem card after the initial demonstration, with each reproduction requiring about 2 hours of preparation and exploitation time.
Physical Access and Laboratory Equipment Required for Exploitation
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, stating: "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 only real risk is a lost or stolen card; if yours stays in your possession, the attack described here cannot be performed."
The researchers noted that Ledger Donjon's lab setup cost about $250,000. For users and custodial service providers, the key exposure is lost, stolen, or unattended wallet cards rather than remote compromise. 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.
Tangem Disputes Practical Significance and Notes Competitor Affiliation
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, stating: "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. 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.
Hardware Wallet Security Implications for Physical Custody
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.
Ledger Donjon said the finding shows that secure element certification does not remove all firmware risk, noting that EAL6+ certification alone does not prevent fault injection attacks if firmware contains exploitable logic flaws. The researchers 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.
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. For investors, exchanges, custodians, and long-term holders, 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.
FAQ
What vulnerability did Ledger Donjon find in Tangem hardware wallet cards?
Ledger Donjon researchers disclosed a security vulnerability that allows an attacker to reset a Tangem card's password through a laser fault injection attack targeting the EAL6+ secure element. The attack bypasses a firmware check verifying whether a card is in an authorized recovery state, enabling password changes without requiring the existing password or backup card. The vulnerability affects all Tangem cards currently in circulation and cannot be patched because the cards lack a firmware update mechanism.
How much does the equipment cost to perform this attack on Tangem cards?
The attack requires specialized laser fault-injection equipment, side-channel analysis tools, and hardware security expertise. Ledger Donjon said its lab setup cost about $250,000. The attack also requires physical possession of the Tangem card and about 2 hours of preparation and exploitation time per card.
How did Tangem respond to the vulnerability disclosure?
Tangem disputed the practical significance of the findings, stating that the attack requires expensive laboratory equipment, physical possession of the card, and specialized expertise, making the risk to everyday users "virtually non-existent." The company also noted that Ledger Donjon operates within Ledger, one of Tangem's largest competitors, and stated that given enough time, funding and access, the firmware on any secure element can eventually be reverse-engineered and exploited.
