How severe is CVE-2021-3672?

CVE-2021-3672 has a CVSS 3.x base score of 5.6, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability low.

Is CVE-2021-3672 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (84th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-3672?

CVE-2021-3672 primarily affects Redhat Enterprise Linux. In total, 32 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-3672?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2021-3672 published?

CVE-2021-3672 was published on 2021-11-23 and last updated on 2026-06-17.

CVE-2021-3672

CVE-2021-3672 is a medium-severity vulnerability in Redhat Enterprise Linux with a CVSS 3.x base score of 5.6. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-79.

Key facts

Severity: Medium (CVSS 3.x base score 5.6)
CVSS v2: 6.8
EPSS exploit prediction: 3% (84th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-79
Affected product: Redhat Enterprise Linux
Published: 2021-11-23
Last modified: 2026-06-17

Description

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.

Frequently asked questions

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.
How severe is CVE-2021-3672?: CVE-2021-3672 has a CVSS 3.x base score of 5.6, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability low.
Is CVE-2021-3672 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (84th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-3672?: CVE-2021-3672 primarily affects Redhat Enterprise Linux. In total, 32 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-3672?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-3672 published?: CVE-2021-3672 was published on 2021-11-23 and last updated on 2026-06-17.

References

Affected products (32)

cpe:2.3:a:c-ares_project:c-ares:*:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux:7.0:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux:7.7:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux_computer_node:1:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux_eus:7.7:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux_eus:8.1:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux_eus:8.2:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux_eus:8.4:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux_for_ibm_z_systems:8.0:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux_for_ibm_z_systems_eus:8.1:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux_for_ibm_z_systems_eus:8.2:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux_for_ibm_z_systems_eus:8.4:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux_for_power_little_endian:8.0:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux_for_power_little_endian_eus:8.1:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux_for_power_little_endian_eus:8.2:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux_for_power_little_endian_eus:8.4:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux_server_aus:8.2:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux_server_aus:8.4:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux_server_tus:8.2:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux_server_tus:8.4:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux_server_update_services_for_sap_solutions:8.1:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux_server_update_services_for_sap_solutions:8.2:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux_server_update_services_for_sap_solutions:8.4:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux_tus:8.4:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux_workstation:1:*:*:*:*:*:*:*
cpe:2.3:a:siemens:sinec_infrastructure_network_services:*:*:*:*:*:*:*:*
cpe:2.3:a:nodejs:node.js:*:*:*:*:-:*:*:*
cpe:2.3:a:nodejs:node.js:*:*:*:*:lts:*:*:*
cpe:2.3:a:pgbouncer:pgbouncer:*:*:*:*:*:*:*:*

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