Doctoral student Raja Hasnain Anwar and Assistant Professor Taqi Raza showed that some expired credit cards can still be used for tap-to-pay purchases, a finding presented at USENIX Security 2026. Using two ordinary smartphones, they rewrote the unprotected expiration date that point-of-sale terminals rely on, and found that not all banks recheck that date against authenticated card data. The team demonstrated the loophole in the lab and at local stores and notified major card companies. ECE announcement