CVE-2021-44732

CRITICALNVD 9.89.8—

9.8

Mbed TLS before 3.0.1 has a double free in certain out-of-memory conditions, as demonstrated by an mbedtls_ssl_set_session() failure.

CVSS v3: 9.8
EG Score: 9.8(medium)
EPSS: 76.7%
KEV: Not listed

Published

December 20, 2021

Last Modified

November 3, 2025

References (15)

cve@mitrehttps://bugs.gentoo.org/829660
cve@mitrehttps://github.com/ARMmbed/mbedtls/releases
cve@mitrehttps://github.com/ARMmbed/mbedtls/releases/tag/v2.16.12
cve@mitrehttps://github.com/ARMmbed/mbedtls/releases/tag/v2.28.0
cve@mitrehttps://github.com/ARMmbed/mbedtls/releases/tag/v3.1.0
cve@mitrehttps://lists.debian.org/debian-lts-announce/2022/12/msg00036.html
cve@mitrehttps://tls.mbed.org/tech-updates/security-advisories/mbedtls-security-advisory-2021-12
af854a3a-2127-422b-91ae-364da2661108https://bugs.gentoo.org/829660
af854a3a-2127-422b-91ae-364da2661108https://github.com/ARMmbed/mbedtls/releases
af854a3a-2127-422b-91ae-364da2661108https://github.com/ARMmbed/mbedtls/releases/tag/v2.16.12
af854a3a-2127-422b-91ae-364da2661108https://github.com/ARMmbed/mbedtls/releases/tag/v2.28.0
af854a3a-2127-422b-91ae-364da2661108https://github.com/ARMmbed/mbedtls/releases/tag/v3.1.0
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
af854a3a-2127-422b-91ae-364da2661108https://tls.mbed.org/tech-updates/security-advisories/mbedtls-security-advisory-2021-12

Patch Availability(1)

Vendor / Ecosystem	Fixed in / Patch	Released	Source
ubuntu	libmbedx509-1t64 (2.28.8-1ubuntu0.1~esm1) @ noble	2026-05-26	ubuntu

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Weakness Classification(1)

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

CWE-415Double Free

All Vendor Advisories

(1)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

UbuntuUSN-8123-1MEDIUM
Mbed TLS vulnerabilities

Data Freshness Timeline

(refreshed 11× in last 7d / 20× 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.

2026-06-02 20:11 UTCepss_batch
2026-06-02 20:11 UTCepss_batch
2026-06-01 13:50 UTCepss_batch
2026-06-01 13:50 UTCepss_batch
2026-05-31 22:29 UTCepss_batch
2026-05-31 22:29 UTCepss_batch
2026-05-31 00:15 UTCepss_batch
2026-05-31 00:15 UTCepss_batch
2026-05-29 13:42 UTCepss_batch
2026-05-28 13:43 UTCepss_batch
2026-05-28 13:43 UTCepss_batch
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 06:06 UTCEG score recompute
2026-05-26 06:06 UTCVendor advisory

Frequently asked(5)

What is CVE-2021-44732?

CVE-2021-44732 is a critical vulnerability published on December 20, 2021. Mbed TLS before 3.0.1 has a double free in certain out-of-memory conditions, as demonstrated by an mbedtlssslset_session() failure.

When was CVE-2021-44732 disclosed?

CVE-2021-44732 was first published in the National Vulnerability Database on December 20, 2021, with the most recent update on November 3, 2025. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.

Is CVE-2021-44732 actively exploited?

CVE-2021-44732 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 76.7% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.

What is the CVSS score of CVE-2021-44732?

CVE-2021-44732 has a CVSS v3 base score of 9.8 (NVD).

How do I remediate CVE-2021-44732?

Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-44732, 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

See which npm, PyPI, Go, and Maven packages are affected by CVE-2021-44732

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