{"id":"CVE-2021-33881","aliases":["EUVD-2021-20554","GHSA-ff8p-pfwc-wjf2"],"status":"published","title":"On NXP MIFARE Ultralight and NTAG cards, an attacker can interrupt a write operation (aka conduct...","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.","severity":{"version":"3.1","score":4.2,"vector":"CVSS:3.1/AV:P/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N","level":"medium","assessor":"primary","from":"nvd"},"epss":{"day":"2026-11-12","score":0.00411,"percentile":0.35867,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-863"],"published":"2021-06-06T15:33:44Z","modified":"2026-06-17T03:55:19Z","products":[{"vendor":"nxp","product":"mifare_ultralight_c_firmware"},{"vendor":"nxp","product":"mifare_ultralight_ev1_firmware"},{"vendor":"nxp","product":"mifare_ultralight_nano_firmware"},{"vendor":"nxp","product":"ntag_210_firmware"},{"vendor":"nxp","product":"ntag_212_firmware"},{"vendor":"nxp","product":"ntag_213_firmware"},{"vendor":"nxp","product":"ntag_215_firmware"},{"vendor":"nxp","product":"ntag_216_firmware"}],"references":[{"url":"https://blog.quarkslab.com/rfid-monotonic-counter-anti-tearing-defeated.html","tags":["x_refsource_MISC","x_transferred","Mitigation","Third Party Advisory"]},{"url":"https://www.nxp.com/docs/en/application-note/AN13089.pdf","tags":["x_refsource_MISC","x_transferred","Vendor Advisory"]},{"url":"https://www.nxp.com/docs/en/application-note/AN11340.pdf","tags":["x_refsource_MISC","x_transferred","Vendor Advisory"]},{"url":"https://www.sstic.org/2021/presentation/eeprom_it_will_all_end_in_tears/","tags":["x_refsource_MISC","x_transferred","Exploit","Third Party Advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2021-33881"},{"url":"https://github.com/advisories/GHSA-ff8p-pfwc-wjf2"}],"sources":{"cve":[{"id":"CVE-2021-33881","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.","status":"published","published":"2021-06-06T15:33:44Z","modified":"2024-08-04T00:05:51.714Z","updated_at":"2026-11-02T14:33:10.555814Z"}],"euvd":[{"id":"EUVD-2021-20554","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.","status":"published","published":"2021-06-06T15:33:44Z","modified":"2024-08-04T00:05:51Z","updated_at":"2026-11-03T03:24:33.318275Z"}],"ghsa":[{"id":"GHSA-ff8p-pfwc-wjf2","title":"On NXP MIFARE Ultralight and NTAG cards, an attacker can interrupt a write operation (aka conduct...","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.","status":"published","published":"2022-05-24T19:04:09Z","modified":"2023-01-29T05:06:26Z","cwes":["CWE-863"],"updated_at":"2026-11-02T14:46:01.439998Z"}],"nvd":[{"id":"CVE-2021-33881","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.","status":"published","published":"2021-06-06T16:15:07.407Z","modified":"2026-06-17T03:55:19.63Z","cvss":[{"version":"3.1","score":4.2,"vector":"CVSS:3.1/AV:P/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N","level":"medium","assessor":"primary"},{"version":"2.0","score":1.9,"vector":"AV:L/AC:M/Au:N/C:N/I:P/A:N","level":"low","assessor":"primary"}],"cwes":["CWE-863"],"updated_at":"2026-11-02T14:06:54.439974Z"}]}}