CVE-2021-43666

HIGHNVD 7.57.5—

7.5

A Denial of Service vulnerability exists in mbed TLS 3.0.0 and earlier in the mbedtls_pkcs12_derivation function when an input password's length is 0.

CVSS v3: 7.5
EG Score: 7.5(medium)
EPSS: 72.6%
KEV: Not listed

Published

March 24, 2022

Last Modified

December 2, 2025

References (5)

cve@mitrehttps://github.com/ARMmbed/mbedtls/issues/5136
cve@mitrehttps://lists.debian.org/debian-lts-announce/2022/12/msg00036.html
af854a3a-2127-422b-91ae-364da2661108https://github.com/ARMmbed/mbedtls/issues/5136
af854a3a-2127-422b-91ae-364da2661108https://lists.debian.org/debian-lts-announce/2022/12/msg00036.html
af854a3a-2127-422b-91ae-364da2661108https://lists.debian.org/debian-lts-announce/2025/06/msg00034.html

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

CWE-130Improper Handling of Length Parameter Inconsistency

Data Freshness Timeline

(refreshed 10× in last 7d / 10× in last 30d)

Every time one of our enrichment pipelines (NVD, MITRE cvelistV5, EPSS, CISA KEV, GHSA, OSV, vendor advisories) ran against this CVE. Most recent first.

2026-05-27 13:39 UTCepss_batch
2026-05-27 13:39 UTCepss_batch
2026-05-26 13:42 UTCepss_batch
2026-05-26 13:42 UTCepss_batch
2026-05-26 07:17 UTCepss_batch
2026-05-26 07:17 UTCepss_batch
2026-05-26 07:17 UTCepss_batch
2026-05-26 01:05 UTCEG score recompute
2026-05-26 01:05 UTCGHSA enrichment
2026-05-25 16:46 UTCOSV refresh

Frequently asked(5)

What is CVE-2021-43666?

CVE-2021-43666 is a high vulnerability published on March 24, 2022. A Denial of Service vulnerability exists in mbed TLS 3.0.0 and earlier in the mbedtlspkcs12derivation function when an input password's length is 0.

When was CVE-2021-43666 disclosed?

CVE-2021-43666 was first published in the National Vulnerability Database on March 24, 2022, with the most recent update on December 2, 2025. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.

Is CVE-2021-43666 actively exploited?

CVE-2021-43666 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 72.6% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.

What is the CVSS score of CVE-2021-43666?

CVE-2021-43666 has a CVSS v3 base score of 7.5 (NVD).

How do I remediate CVE-2021-43666?

Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-43666, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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CVE-2021-43666

📅 Published

🔄 Last Modified

🔗 References (5)