CVE-2020-12663 : Security Advisory and Response

Unbound before 1.10.1 has an infinite loop via malformed DNS answers received from upstream servers.

Understanding CVE-2020-12663

Unbound before version 1.10.1 is susceptible to an infinite loop caused by improperly formatted DNS responses.

What is CVE-2020-12663?

CVE-2020-12663 is a vulnerability in Unbound, a validating, recursive, and caching DNS resolver.

The Impact of CVE-2020-12663

This vulnerability could lead to a denial of service (DoS) condition due to the infinite loop, potentially disrupting DNS resolution services.

Technical Details of CVE-2020-12663

Unbound before 1.10.1 experiences an infinite loop triggered by malformed DNS responses.

Vulnerability Description

The issue arises from incorrectly formatted DNS answers received from upstream servers.

Affected Systems and Versions

Unbound versions prior to 1.10.1 are affected by this vulnerability.

Exploitation Mechanism

Attackers can exploit this vulnerability by sending specially crafted DNS responses to the affected Unbound server, triggering the infinite loop.

Mitigation and Prevention

Steps to address and prevent the CVE-2020-12663 vulnerability.

Immediate Steps to Take

Update Unbound to version 1.10.1 or later to mitigate the infinite loop issue.
Monitor DNS traffic for any signs of abnormal behavior that could indicate exploitation.

Long-Term Security Practices

Regularly update and patch DNS resolver software to address known vulnerabilities.
Implement network-level protections to filter out potentially malicious DNS responses.

Patching and Updates

Stay informed about security advisories and promptly apply patches released by Unbound to address vulnerabilities like CVE-2020-12663.