What is the CVSS score of CVE-2021-33881?

CVE-2021-33881 has a CVSS 3.1 base score of 4.2 (Medium). CVSS vector: CVSS:3.1/AV:P/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N. EPSS exploitation probability: 0.4%.

Is there a public PoC exploit available for CVE-2021-33881?

Yes, a public proof-of-concept exploit is available for CVE-2021-33881. Prioritise patching immediately. EPSS: 0.4%.

Mifare Ultralight Ev1 Firmware CVE-2021-33881

MEDIUM

Incorrect Authorization (CWE-863)

2021-06-06 cve@mitre.org

Authentication Bypass 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

4.2

CVSS 3.1 · NVD

Severity by source

NVD PRIMARY

4.2 MEDIUM

AV:P/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

CVSS:3.1/AV:P/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N

Attack Vector

Physical

Attack Complexity

High

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

High

Availability

None

Lifecycle Timeline

CVE Published

Jun 06, 2021 - 16:15 nvd

MEDIUM 4.2

DescriptionNVD

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.

AnalysisAI

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. Rated medium severity (CVSS 4.2), this vulnerability is no authentication required. Public exploit code available and no vendor patch available.

Technical ContextAI

This vulnerability is classified as Incorrect Authorization (CWE-863), which allows attackers to bypass authorization checks to access restricted resources. 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 products include: Nxp Mifare Ultralight Ev1 Firmware, Nxp Mifare Ultralight C Firmware, Nxp Mifare Ultralight Nano Firmware, Nxp Ntag 210 Firmware, Nxp Ntag 212 Firmware.

RemediationAI

No vendor patch is available at time of analysis. Monitor vendor advisories for updates. Review and test authorization logic, implement consistent access control checks, use centralized authorization framework.