The result is not a universal way to use every expired card. It is a payment-chain weakness that depends on the card network’s contactless implementation, the terminal, and—crucially—the issuer’s authorization checks.

What the Zombie Card attack does

The attack sits between an expired physical contactless card and a checkout terminal. One smartphone communicates with the card, while a second presents the card’s responses to the terminal; the phones relay the exchange over a network connection. During that exchange, the relay changes the expiration date that the terminal sees to a date in the future.

The researchers reported that the attacker does not need to know the expiration date of a replacement card. In the terminal-side check they described, an arbitrary future date can be enough to make the card appear current.

That does not mean the attacker has forged the card or defeated EMV cryptography. The physical card still supplies its genuine card data, signatures, and transaction cryptograms. The problem is that the expiration value used by the terminal is not adequately tied to the authenticated information later used for online authorization in the tested Visa setup.

Why Visa EMV Kernel 3 matters

EMV kernels are the payment-processing software implementations used by terminals for different card schemes. Visa, Mastercard, American Express, and Discover use distinct contactless processing paths.

The researchers’ finding concerned Visa’s EMV contactless path, identified in the supplied reporting as Kernel 3. The reported design gap allows two parts of the transaction to disagree: the terminal can receive a modified, future expiration date, while the issuer-facing transaction retains authentic card data and valid cryptographic checks.

In a more tightly bound design, changing the expiration-related value in transit would make the authenticated transaction inconsistent and cause validation to fail. The Zombie Card finding therefore illustrates an important security principle: cryptographic protection is less useful when a security-critical field is checked in one part of the payment chain but not reliably bound to the data trusted elsewhere.

Why the same technique reportedly failed on other networks

The researchers tested the approach against other contactless kernels and reported that it did not work against Mastercard Kernel 2, American Express Kernel 4, or Discover Kernel 6. The supplied reports attribute that resistance to stronger protection, validation, or cryptographic binding of the relevant expiration data.

The available evidence does not establish the exact protocol-level rule that stops the attack in each of those three kernels. It is therefore safer to state the conclusion narrowly: the demonstrated expiry-tampering method was reported as effective against the tested Visa setup, but not against the tested Mastercard, American Express, and Discover paths. It is not evidence that Visa cards are generally forgeable or that every expired Visa card will work.

What testing at five U.S. banks showed

Testing across merchants, terminals, EMV kernels, and five major U.S. banks produced mixed results. Some issuers authorized transactions containing the altered terminal-side expiration date, while others rejected them because of stronger issuer-side checks.

That variation is central to the finding. The terminal’s acceptance decision alone did not determine whether the payment completed; the issuer’s authorization logic also mattered. A bank that independently enforces card expiration, replacement, cancellation, and account lifecycle status is more likely to reject the transaction than one that relies heavily on the terminal’s expiry decision.

The supplied reporting does not provide a reliable bank-by-bank list of the five institutions, exact approval and rejection results, or verified transaction limits for each bank. Those details should not be inferred from the broader finding.

Disclosure and remediation status

The research was presented at USENIX Security 2026, and the supplied university-related reporting says that major card companies were notified before the findings were made public.

As of August 20, 2026, the supplied evidence confirms the vulnerability finding in the researchers’ evaluation but does not confirm that Visa had completed a universal kernel change, terminal update, or issuer-wide fix. It also does not establish a definitive remediation timeline for each affected bank.

That distinction matters: disclosure is not the same as completed remediation. The practical risk can vary while networks, terminal providers, acquirers, and issuers determine how to validate the relevant card-lifecycle data consistently.

Recommended defenses across the payment chain

The research points to defense in depth rather than a single fix:

• Payment-kernel and card-system designers: cryptographically bind the expiration date and other lifecycle fields visible to the terminal to the authenticated transaction data. An in-transit change should invalidate the transaction.
• Terminal and acquiring systems: validate expiration using authenticated information where available and reject inconsistent values instead of trusting an unprotected terminal-facing field.
• Issuers: independently check expiration, replacement, cancellation, and account status during authorization rather than relying only on the terminal’s local decision.
• Networks and fraud teams: look for discrepancies between terminal-provided expiry data and issuer-visible card information, while applying controls appropriate for suspicious contactless relay activity. This follows from the researchers’ finding that responsibility is split across the card, terminal, network, and issuer.

What consumers should do with expired cards

An expired card should not be thrown away intact. The guidance supplied with the research recommends demagnetizing the magnetic stripe, destroying the EMV chip, and cutting or shredding the card—including its printed numbers and letters—before discarding the pieces separately. Owners of metal cards should ask the issuer how to dispose of them safely.

Cardholders should also monitor the associated account, including after a card has been closed, and report unauthorized charges promptly. The attack requires access to the physical card or sustained proximity to it, so securely destroying an old card reduces the opportunity for abuse.

The result is not a universal way to use every expired card. It is a payment-chain weakness that depends on the card network’s contactless implementation, the terminal, and—crucially—the issuer’s authorization checks.

What the Zombie Card attack does

The attack sits between an expired physical contactless card and a checkout terminal. One smartphone communicates with the card, while a second presents the card’s responses to the terminal; the phones relay the exchange over a network connection. During that exchange, the relay changes the expiration date that the terminal sees to a date in the future.

The researchers reported that the attacker does not need to know the expiration date of a replacement card. In the terminal-side check they described, an arbitrary future date can be enough to make the card appear current.

That does not mean the attacker has forged the card or defeated EMV cryptography. The physical card still supplies its genuine card data, signatures, and transaction cryptograms. The problem is that the expiration value used by the terminal is not adequately tied to the authenticated information later used for online authorization in the tested Visa setup.

Why Visa EMV Kernel 3 matters

EMV kernels are the payment-processing software implementations used by terminals for different card schemes. Visa, Mastercard, American Express, and Discover use distinct contactless processing paths.

The researchers’ finding concerned Visa’s EMV contactless path, identified in the supplied reporting as Kernel 3. The reported design gap allows two parts of the transaction to disagree: the terminal can receive a modified, future expiration date, while the issuer-facing transaction retains authentic card data and valid cryptographic checks.

In a more tightly bound design, changing the expiration-related value in transit would make the authenticated transaction inconsistent and cause validation to fail. The Zombie Card finding therefore illustrates an important security principle: cryptographic protection is less useful when a security-critical field is checked in one part of the payment chain but not reliably bound to the data trusted elsewhere.

Why the same technique reportedly failed on other networks

The researchers tested the approach against other contactless kernels and reported that it did not work against Mastercard Kernel 2, American Express Kernel 4, or Discover Kernel 6. The supplied reports attribute that resistance to stronger protection, validation, or cryptographic binding of the relevant expiration data.

The available evidence does not establish the exact protocol-level rule that stops the attack in each of those three kernels. It is therefore safer to state the conclusion narrowly: the demonstrated expiry-tampering method was reported as effective against the tested Visa setup, but not against the tested Mastercard, American Express, and Discover paths. It is not evidence that Visa cards are generally forgeable or that every expired Visa card will work.

What testing at five U.S. banks showed

Testing across merchants, terminals, EMV kernels, and five major U.S. banks produced mixed results. Some issuers authorized transactions containing the altered terminal-side expiration date, while others rejected them because of stronger issuer-side checks.

That variation is central to the finding. The terminal’s acceptance decision alone did not determine whether the payment completed; the issuer’s authorization logic also mattered. A bank that independently enforces card expiration, replacement, cancellation, and account lifecycle status is more likely to reject the transaction than one that relies heavily on the terminal’s expiry decision.

The supplied reporting does not provide a reliable bank-by-bank list of the five institutions, exact approval and rejection results, or verified transaction limits for each bank. Those details should not be inferred from the broader finding.

Disclosure and remediation status

The research was presented at USENIX Security 2026, and the supplied university-related reporting says that major card companies were notified before the findings were made public.

As of August 20, 2026, the supplied evidence confirms the vulnerability finding in the researchers’ evaluation but does not confirm that Visa had completed a universal kernel change, terminal update, or issuer-wide fix. It also does not establish a definitive remediation timeline for each affected bank.

That distinction matters: disclosure is not the same as completed remediation. The practical risk can vary while networks, terminal providers, acquirers, and issuers determine how to validate the relevant card-lifecycle data consistently.

Recommended defenses across the payment chain

The research points to defense in depth rather than a single fix:

• Payment-kernel and card-system designers: cryptographically bind the expiration date and other lifecycle fields visible to the terminal to the authenticated transaction data. An in-transit change should invalidate the transaction.
• Terminal and acquiring systems: validate expiration using authenticated information where available and reject inconsistent values instead of trusting an unprotected terminal-facing field.
• Issuers: independently check expiration, replacement, cancellation, and account status during authorization rather than relying only on the terminal’s local decision.
• Networks and fraud teams: look for discrepancies between terminal-provided expiry data and issuer-visible card information, while applying controls appropriate for suspicious contactless relay activity. This follows from the researchers’ finding that responsibility is split across the card, terminal, network, and issuer.

What consumers should do with expired cards

An expired card should not be thrown away intact. The guidance supplied with the research recommends demagnetizing the magnetic stripe, destroying the EMV chip, and cutting or shredding the card—including its printed numbers and letters—before discarding the pieces separately. Owners of metal cards should ask the issuer how to dispose of them safely.

Cardholders should also monitor the associated account, including after a card has been closed, and report unauthorized charges promptly. The attack requires access to the physical card or sustained proximity to it, so securely destroying an old card reduces the opportunity for abuse.