Insufficient Encryption Level in CasfID Servicios Tecnológicos NFC Wristbands
MIFARE Classic chip family: FM11RF08S variant.
INCIBE has coordinated the disclosure of a high-severity vulnerability affecting CasfID Servicios Tecnológicos’ cashless payment system using NFC wristbands. The vulnerability was discovered by Luis Miranda Acebedo.
This vulnerability has been assigned the following code, CVSS v4.0 base score, CVSS vector, and CWE vulnerability type:
- CVE-2026-4648: CVSS v4.0: 6.8 | CVSS AV:P/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N | CWE-326
Since the vulnerability stems from a hardware-level cryptographic weakness inherent in the MIFARE Classic family, it is recommended to discontinue the use of these chips (such as the FM11RF08S variant) for payment systems and critical access control systems. As a definitive solution, organizations should migrate to smart card technologies that support robust, up-to-date cryptographic standards (such as AES-128 or higher), such as the MIFARE DESFire family (EV2 or EV3).
CVE-2026-4648: use of an insecure cryptographic algorithm in the cashless payment system using NFC wristbands from CasfID Servicios Tecnológicos S.L.U. (version used at Resurrection Fest 2025), which employs cards based on MIFARE Classic technology (FM11RF08S). The cryptographic weakness of the authentication algorithm allows an attacker to retrieve access keys using techniques known as Backdoored Nested Attack, read the wristband’s entire contents, and clone its credentials onto a compatible rewritable card. Exploitation of this vulnerability could enable the impersonation of other attendees, the fraudulent use of the balance associated with their wristbands, and financial losses for both the affected users and the event organizers.
| Identificador CVE | Severidad | Explotación | Fabricante |
|---|---|---|---|
| CVE-2026-4648 | Media | No | MIFARE |
