CVE-2021-43666

Exploitation

Public exploit code exists. CISA's assessment records a public proof of concept. That is not a report of exploitation in the wild.

SSVC decision

• ExploitationpocPublic proof-of-concept exploit code exists. Not a report of exploitation in the wild.
• AutomatableyesAn attacker can reliably automate reconnaissance through exploitation, so this scales.
• Technical ImpactpartialSuccessful exploitation gives limited control of the vulnerable component.

CISA publishes the decision points, not a final SSVC decision. The decision also depends on mission and well-being impact, which is a property of your deployment rather than of the vulnerability.

EPSS probability

2.06% probability of exploitation activity in the next 30 days.

EPSS percentile

Equal to or higher than the score of 81.0% of scored records. A rank, not a probability.

NVD base score

7.5 (CVSS v3.x), scored by the NVD independently of the CNA.

NVD CVSS vector

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

NVD analysis status

Modified. NVD last modified this record on 2026-06-17.

Red Hat severity

No Red Hat rating. Red Hat rates the CVEs that affect its products.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

Published

2022-03-24 00:00Z4 YR AGO

Last updated

2025-12-02 20:51Z11 MO AGO

Reserved

2021-11-15

Assigning CNA

mitre

Record state

PUBLISHED

Severity

High (CVSS 7.5)

CNA CVSS vector

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

Weaknesses

• CWE-130Improper Handling of Length Parameter InconsistencyBase

Data version

5.2

Document digest

6cfe13cef68f7d5c05ffd128d1e072d20a184c9fa0301a6c1df1f9dff40ef040

• github.comhttps://github.com/ARMmbed/mbedtls/issues/5136
• lists.debian.org[debian-lts-announce] 20221225 [SECURITY] [DLA 3249-1] mbedtls security updatehttps://lists.debian.org/debian-lts-announce/2022/12/msg00036.htmlmailing-list
• lists.debian.orghttps://lists.debian.org/debian-lts-announce/2025/06/msg00034.html