CVE-2021-1446 Explained : Impact and Mitigation

A vulnerability in the DNS application layer gateway (ALG) functionality in Cisco IOS XE Software could allow an unauthenticated remote attacker to cause a denial of service (DoS) condition on an affected device.

Understanding CVE-2021-1446

This CVE refers to a denial of service vulnerability in the DNS ALG feature of Cisco IOS XE Software.

What is CVE-2021-1446?

The vulnerability in the DNS ALG feature of Cisco IOS XE Software allows a remote attacker to send crafted DNS packets, causing the affected device to reload and resulting in a DoS condition.

The Impact of CVE-2021-1446

The vulnerability's high severity rating of 8.6 can lead to a complete denial of service on the affected device, affecting network availability.

Technical Details of CVE-2021-1446

The vulnerability arises due to a logic error when inspecting certain DNS packets on affected devices performing NAT for DNS packets.

Vulnerability Description

The flaw allows attackers to exploit the DNS ALG feature by sending maliciously crafted DNS packets via IPv4, leading to device reloads.

Affected Systems and Versions

Cisco IOS XE Software is affected by this vulnerability, impacting devices performing NAT for DNS packets.

Exploitation Mechanism

Attackers take advantage of the vulnerability by sending crafted DNS packets through devices, which triggers device reloads and causes DoS.

Mitigation and Prevention

To mitigate the risks associated with CVE-2021-1446, immediate steps and long-term security practices are recommended.

Immediate Steps to Take

Cisco advises applying official patches and workarounds provided in their security advisory to address the vulnerability.

Long-Term Security Practices

Regularly monitor Cisco's security advisories and update systems promptly to prevent exploitation of vulnerabilities.

Patching and Updates

Stay informed about security updates from Cisco and apply patches as soon as they are released to protect against potential threats.