CVE-2025-59030 is a vulnerability classified under CWE-276 (Incorrect Default Permissions) affecting PowerDNS Recursor versions 5.1.0, 5.2.0, and 5.3.0. The flaw allows an unauthenticated attacker to send a specially crafted NOTIFY query over TCP to the DNS recursor service, which triggers the removal of cached DNS records. This cache invalidation leads to a denial of service (DoS) condition by forcing the DNS resolver to repeatedly query upstream servers, increasing latency and potentially overwhelming the resolver or upstream infrastructure. The vulnerability arises due to improper handling of NOTIFY queries and insufficient permission checks or validation on these requests. The attack vector is network-based (AV:N), requires no privileges (PR:N), no user interaction (UI:N), and affects the availability (A:H) of the service without compromising confidentiality or integrity. The vulnerability was publicly disclosed on December 9, 2025, with no known exploits in the wild at the time of publication. PowerDNS Recursor is widely used in DNS infrastructure for recursive resolution, making this vulnerability significant for DNS service stability. The absence of patches at the time of disclosure necessitates immediate mitigation efforts to prevent exploitation.

For European organizations, the primary impact of CVE-2025-59030 is on the availability of DNS resolution services. DNS is a critical component of network infrastructure, and disruption can lead to widespread service outages, degraded performance, and potential cascading failures in dependent applications and services. Organizations relying on PowerDNS Recursor for internal or external DNS resolution may experience increased latency, failed domain resolutions, or temporary denial of service. This can affect enterprises, ISPs, cloud providers, and critical infrastructure operators. The lack of impact on confidentiality or integrity reduces risks of data breaches or manipulation, but availability issues can still cause significant operational and financial damage. In sectors such as finance, healthcare, telecommunications, and government, DNS outages can disrupt essential services and erode trust. Additionally, attackers could leverage this vulnerability as part of a larger attack chain to degrade network defenses or distract security teams.

1. Monitor DNS traffic for unusual or unexpected NOTIFY queries over TCP and implement alerting mechanisms. 2. Apply vendor patches promptly once available to address the underlying permission and validation issues. 3. In the interim, restrict or block incoming TCP NOTIFY queries at the network perimeter or firewall to prevent exploitation. 4. Harden DNS recursor configurations by disabling unnecessary features or query types if possible. 5. Employ rate limiting on DNS queries to mitigate potential DoS amplification. 6. Conduct regular audits of DNS server configurations and permissions to ensure adherence to security best practices. 7. Use network segmentation to isolate DNS infrastructure and limit exposure to untrusted networks. 8. Collaborate with upstream DNS providers and peers to detect and respond to anomalous DNS traffic patterns. 9. Prepare incident response plans specific to DNS service disruptions to minimize downtime and impact.