CVE-2022-3204

Name of the Vulnerable Software and Affected Versions Unbound versions prior to 1.16.3

Description The issue is related to a Non-Responsive Delegation Attack (NRDelegation Attack) that affects various DNS resolving software, including Unbound. This attack involves a malicious delegation with a considerable number of non-responsive nameservers, causing the resolver to spend significant time and resources resolving records under the malicious delegation point. Although Unbound does not suffer from high CPU usage, it still requires resources to resolve the malicious delegation, which can lead to degraded performance and potentially a denial of service in orchestrated attacks.

Recommendations For Unbound versions prior to 1.16.3, update to version 1.16.3 or later, which introduces fixes for better performance when under load by cutting opportunistic queries for nameserver discovery and DNSKEY prefetching, and limiting the number of times a delegation point can issue a cache lookup for missing records.