Is CVE-2021-1446 being actively exploited?

CVE-2021-1446 is not currently listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.

What is the CVSS score for CVE-2021-1446?

CVE-2021-1446 has a CVSS 3.1 base score of 8.6 (HIGH).

CVE-2021-1446

HIGH · CVSS 8.6EPSS 1.5%EU EUVD

A vulnerability in the DNS application layer gateway (ALG) functionality used by Network Address Translation (NAT) in Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause an affected device to reload. The vulnerability is due to a logic error that occurs when an affected device inspects certain DNS packets. An attacker could exploit this vulnerability by sending crafted DNS packets through an affected device that is performing NAT for DNS packets. A successful exploit could allow an attacker to cause the device to reload, resulting in a denial of service (DoS) condition on an affected device. The vulnerability can be exploited only by traffic that is sent through an affected device via IPv4 packets. The vulnerability cannot be exploited via IPv6 traffic.

Key facts

CVSS score: 8.6 (v3.1)
Severity: HIGH
CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
Weakness (CWE): CWE-754
EPSS score: 1.5% (75th percentile)
In CISA KEV: No
In EU EUVD: Yes (EUVD-2021-6913)
Published: March 24, 2021
NVD last modified: June 17, 2026
Status: Modified

EU Vulnerability Database (EUVD)

This vulnerability is also tracked by ENISA as EUVD-2021-6913 in the EU Vulnerability Database. Last updated in EUVD on November 8, 2024.

View on the EU Vulnerability Database

Affected products

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and 215 more…

Certified products that may be affected

3 FIPS 140 or Common Criteria certified products, from automated matching by sec-certs.org.

Cisco Aggregation Services Router (ASR) 1000 Series, IOS XE 3.13 - Cisco Systems, Inc. - Common Criteria CCEVS-VR-VID-10609-2015 - archived
Cisco Integrated Services Router 4400 Series (ISR-4400), IOS XE 3.13.0 - Cisco Systems, Inc. - Common Criteria CCEVS-VR-VID-10600-2015 - archived
Cisco Integrated Services Routers Series (ISR-4400), IOS XE 3.10.2tS - Cisco Systems, Inc. - Common Criteria CCEVS-VR-VID-10553-2014 - archived

References

https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-alg-dos-hbBS7SZE(Vendor Advisory)

Last updated September 17, 2026 · Source: NVD, CISA KEV, FIRST.org EPSS

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