Auth bypass in Nxp Mifare Ultralight C
CVE-2021-33881
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.
Vulnerability class: Broken Access Control
EPSS: 0.004 (33.7th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 4.2 (Medium). Vector: CVSS:3.1/AV:P/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N.
Affected products
Weakness classification (CWE)
Public proof-of-concept exploits
References
- cve@mitre.org (Third Party Advisory, x_refsource_MISC, Mitigation)
- cve@mitre.org (x_refsource_MISC, Vendor Advisory)
- cve@mitre.org (x_refsource_MISC, Vendor Advisory)
- cve@mitre.org (Exploit, Third Party Advisory, x_refsource_MISC)
Frequently asked questions
- What is CVE-2021-33881?
- CVE-2021-33881 is a medium-severity vulnerability in Nxp Mifare Ultralight C, classified under Incorrect Authorization. CVSS score: 4.2/10. Published 2021-06-06.
- How severe is CVE-2021-33881?
- Medium severity. CVSS v3 base score is 4.2 out of 10.
- Is CVE-2021-33881 known to be exploited?
- 2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.