CVE-2021-33881: Medium severity nxp mifare ultralight ev1 firmware vulnerability

Published Jun 6, 2021
·
Updated

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.

Affected Software

16 affected components
NXP Mifare Ultralight Ev1 Firmware
NXP Mifare Ultralight Ev1
NXP Mifare Ultralight C Firmware
NXP Mifare Ultralight C
NXP Mifare Ultralight Nano Firmware
NXP Mifare Ultralight Nano
NXP Ntag 210 Firmware
NXP Ntag 210
NXP Ntag 212 Firmware
NXP Ntag 212
NXP Ntag 213 Firmware
NXP Ntag 213
NXP Ntag 215 Firmware
NXP Ntag 215
NXP Ntag 216 Firmware
NXP Ntag 216

Event History

Jun 6, 2021
CVE Published
via MITRE·03:33 PM
Data Sourced
via MITRE·03:33 PM
Description
Free Weekly Intel

Don't miss critical vulnerabilities

Join thousands of security professionals who receive our weekly digest of trending CVEs, zero-days, and exploited vulnerabilities.

No spam. Unsubscribe anytime.

Frequently Asked Questions

1

What is CVE-2021-33881?

CVE-2021-33881 is a vulnerability that allows an attacker to interrupt a write operation on NXP MIFARE Ultralight and NTAG cards, bypassing a Monotonic Counter protection mechanism.

2

What is the severity of CVE-2021-33881?

CVE-2021-33881 has a severity rating of 4.2 (medium).

3

How does CVE-2021-33881 impact public transportation?

The impact of CVE-2021-33881 on public transportation depends on how the anti tear-off feature is used in specific applications.

4

Are there any resources to learn more about CVE-2021-33881?

Yes, you can refer to the following resources for more information: [An article on RFID Monotonic Counter Anti-Tearing Defeated](https://blog.quarkslab.com/rfid-monotonic-counter-anti-tearing-defeated.html), [NXP Application Note AN11340](https://www.nxp.com/docs/en/application-note/AN11340.pdf), [NXP Application Note AN13089](https://www.nxp.com/docs/en/application-note/AN13089.pdf).

5

What is the Common Weakness Enumeration (CWE) ID associated with CVE-2021-33881?

CVE-2021-33881 is associated with CWE-863.

Contact

SecAlerts Pty Ltd.
132 Wickham Terrace
Fortitude Valley,
QLD 4006, Australia
info@secalerts.co
By using SecAlerts services, you agree to our services end-user license agreement. This website is safeguarded by reCAPTCHA and governed by the Google Privacy Policy and Terms of Service. All names, logos, and brands of products are owned by their respective owners, and any usage of these names, logos, and brands for identification purposes only does not imply endorsement. If you possess any content that requires removal, please get in touch with us.
© 2026 SecAlerts Pty Ltd.
ABN: 70 645 966 203, ACN: 645 966 203