CVE-2021-1446

CVE-2021-1446 is a high-severity vulnerability in Cisco Ios Xe with a CVSS 3.x base score of 8.6. 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-754.

Key facts

Description

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.

Frequently asked questions

What is CVE-2021-1446?
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.
How severe is CVE-2021-1446?
CVE-2021-1446 has a CVSS 3.x base score of 8.6, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2021-1446 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (71st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-1446?
CVE-2021-1446 primarily affects Cisco Ios Xe. In total, 265 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-1446?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-1446 published?
CVE-2021-1446 was published on 2021-03-24 and last updated on 2026-06-17.

References

Affected products (265)

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