MEDIUM
CVE-2021-33881
CWE-863Published: June 6, 2021· Updated: Jun 17, 2026
4.2
CVSS v3.1
Official Description
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.
Technical Analysis
CVE-2021-33881 requires local access, meaning attackers must already have a foothold on the target system.
The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.
A successful exploit results in full integrity compromise (data manipulation), with a CVSS base score of 4.2.
CVSS v3.1 Vector Breakdown
Exploitability
Attack VectorPhysical
Attack ComplexityHigh
Privileges Req.None
User InteractionNone
ScopeUnchanged
Impact
ConfidentialityNone
IntegrityHigh
AvailabilityNone
CVSS:3.1/AV:P/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N
Affected Vendors & Products
nxp16 product(s)
mifare ultralight ev1 firmwaremifare ultralight ev1mifare ultralight c firmwaremifare ultralight cmifare ultralight nano firmwaremifare ultralight nanontag 210 firmwarentag 210ntag 212 firmwarentag 212ntag 213 firmwarentag 213+4
Source: NVD CPE · 16 total CPE entries
Exploit & PoC Resources
NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
External links open in a new tab. Always verify in a controlled environment before use.
Official Patches & Advisories
All References (8)
→
https://blog.quarkslab.com/rfid-monotonic-counter-anti-tearing-defeated.htmlMitigation · Third Party Advisory
→
https://www.nxp.com/docs/en/application-note/AN11340.pdfVendor Advisory
→
https://www.nxp.com/docs/en/application-note/AN13089.pdfVendor Advisory
→
https://www.sstic.org/2021/presentation/eeprom_it_will_all_end_in_tears/Exploit · Third Party Advisory
→
https://blog.quarkslab.com/rfid-monotonic-counter-anti-tearing-defeated.htmlMitigation · Third Party Advisory
→
https://www.nxp.com/docs/en/application-note/AN11340.pdfVendor Advisory
→
https://www.nxp.com/docs/en/application-note/AN13089.pdfVendor Advisory
→
https://www.sstic.org/2021/presentation/eeprom_it_will_all_end_in_tears/Exploit · Third Party Advisory
Quick Facts
CVE IDCVE-2021-33881
CVSS Score4.2 / 10
SeverityMEDIUM
WeaknessCWE-863
CISA KEVNo
Affected1 vendor(s)
PublishedJun 6, 2021
Related CVEs (CWE-863)
Recommended Actions
- →Apply vendor patches immediately
- →Monitor CVE-2021-33881 in threat intel feeds
- →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWatch. CVE data is provided under the NVD usage policy.