CVE-2021-33881

low-risk
Published 2021-06-06

On NXP MIFARE Ultralight and NTAG cards, an attacker can interrupt a write operation (aka conduct a "tear off" attack) over RFID to bypass a Monotonic Counter protection mechanism. The impact depends on how the anti tear-off feature is used in specific applications such as public transportation, physical access control, etc.

Do I need to act?

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0.06% chance of exploitation
EPSS score — low exploit probability
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Not on CISA KEV list
No confirmed active exploitation reported to CISA
?
Patch status unknown
Check vendor advisories for fix availability and mitigation guidance
4
CVSS 4.2/10 Medium
PHYSICAL / HIGH complexity

Affected Products (8)

Mifare Ultralight Ev1 Firmware
Mifare Ultralight C Firmware
Mifare Ultralight Nano Firmware
Ntag 210 Firmware
Ntag 212 Firmware
Ntag 213 Firmware
Ntag 215 Firmware
Ntag 216 Firmware

Affected Vendors

Nxp

References (8)

Mitigation https://blog.quarkslab.com/rfid-monotonic-counter-anti-tearing-defeated.html
Vendor Advisory https://www.nxp.com/docs/en/application-note/AN11340.pdf
Vendor Advisory https://www.nxp.com/docs/en/application-note/AN13089.pdf
Exploit https://www.sstic.org/2021/presentation/eeprom_it_will_all_end_in_tears/
Mitigation https://blog.quarkslab.com/rfid-monotonic-counter-anti-tearing-defeated.html
Vendor Advisory https://www.nxp.com/docs/en/application-note/AN11340.pdf
Vendor Advisory https://www.nxp.com/docs/en/application-note/AN13089.pdf
Exploit https://www.sstic.org/2021/presentation/eeprom_it_will_all_end_in_tears/
25
/ 100
low-risk
Severity 11/34 · Low
Exploitability 0/34 · Minimal
Exposure 14/34 · Moderate