Published Nov 23, 2021Sources checked Nov 11, 2026
5.6MEDIUMCVSS out of 10
What this means
Review the available evidence
CVE-2021-3672 and is rated Medium severity with a CVSS score of 5.6. It is not in the current CISA KEV record we collected. That does not prove exploitation has not occurred.
What to do next
Remediation and response
Microsoft Security Response Center guidance
Vendor revision: Aug 12, 2026
CBL-Mariner Releases
Vendor-listed releases
1.16.1-1
1.18.1-1
18.2.2-1
CISA KEVNot listedBased on the latest collected catalog
EPSS2.8%Estimated 30-day exploitation probability
Ransomware useNot markedCISA KEV ransomware field
Threat actors0Source-linked actor relationships
Overview
What is CVE-2021-3672?
A flaw was found in c-ares library, where a missing input validation check of host names returned by DNS (Domain Name Servers) can lead to output of wrong hostnames which might potentially lead to Domain Hijacking. The highest threat from this vulnerability is to confidentiality and integrity as well as system availability.