Ledger researchers disclose Tangem card flaw; Tangem says risk to everyday users is 'virtually non-existent'

Ledger Donjon researchers disclosed a security vulnerability in Tangem hardware wallet cards that allows an attacker to reset the card’s password through a laser fault injection attack. 

The exploit requires physical access to a Tangem card, specialized laser fault-injection equipment, side-channel analysis tools, and hardware security expertise. Ledger Donjon said in a blog post that its laboratory setup cost about $250,000, while the vulnerability affects all Tangem cards currently in circulation and cannot be patched because the cards lack a firmware update mechanism. 

According to the post, researchers prepared the card by exposing the secure element and connecting it to custom hardware before using a nanosecond laser pulse to target a specific area of the chip. 

The fault injection bypassed the firmware check that verifies whether a card is in an authorized recovery state, allowing the SetPin instruction to accept a new password without the existing password or backup card.

Implications 

Once the password is reset, an attacker gains control of the wallet and can use the card to sign transactions, allowing funds associated with the wallet to be moved.

Ledger Donjon said it reproduced the attack on a second and third card after demonstrating the initial exploit, with each reproduction requiring about two hours of preparation and exploitation time.

“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.”

The researchers recommended that secure element firmware use multiple independent checks for sensitive operations, strengthen state validation methods, and ensure password changes remain protected when recovery features are disabled. They said EAL6+ certification alone does not prevent fault injection attacks if firmware contains exploitable logic flaws.

Prior to this discovery, the researchers had uncovered a genuine check bypass on the Tangem Android application and a brute-force attack on the card's authentication protocol. The vulnerability was disclosed to Tangem in February. 

Tangem responds

In a post on X following Ledger Donjon's disclosure, Tangem disputed the practical significance of the findings, highlighting the attack requires expensive laboratory equipment, physical possession of the card, and specialized expertise, making the risk to everyday users "virtually non-existent."

"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."