CVE-2025-59029 is a vulnerability identified in PowerDNS Recursor version 5.3.0 that involves a reachable assertion failure (CWE-617). The flaw can be triggered remotely by an unauthenticated attacker who crafts specific DNS records and waits for them to be cached by the resolver. Subsequently, the attacker sends a DNS query with the query type (qtype) set to ANY, which causes the software to hit an assertion failure within its codebase. This assertion failure leads to a crash of the PowerDNS Recursor process, resulting in a denial of service (DoS) condition. The vulnerability does not impact confidentiality or integrity but affects availability by disrupting DNS resolution services. The CVSS 3.1 base score is 5.3, reflecting medium severity, with attack vector as network (AV:N), low attack complexity (AC:L), no privileges required (PR:N), no user interaction (UI:N), and scope unchanged (S:U). No patches or exploits are currently publicly available, but the vulnerability is documented and published. PowerDNS Recursor is widely used in DNS infrastructure, including by ISPs and enterprises, making this a notable risk. The vulnerability arises from improper handling of cached DNS records and the ANY query type, which is often used in DNS enumeration or amplification attacks. This issue highlights the importance of robust input validation and error handling in DNS software.

The primary impact of CVE-2025-59029 is a denial of service against DNS resolution services running PowerDNS Recursor 5.3.0. For European organizations, this can disrupt critical network services, internal and external name resolution, and potentially impact business operations relying on DNS availability. Organizations providing DNS services to customers or hosting critical infrastructure are particularly vulnerable, as DNS outages can cascade into broader service disruptions. The vulnerability does not expose sensitive data or allow code execution, but the loss of availability can degrade trust and operational continuity. In sectors such as finance, telecommunications, government, and critical infrastructure within Europe, DNS service interruptions can have significant operational and reputational consequences. Additionally, attackers could leverage this vulnerability as part of a larger attack chain to cause service outages or to distract from other malicious activities. The lack of authentication and user interaction requirements makes exploitation feasible by remote attackers, increasing the risk profile.

To mitigate CVE-2025-59029, organizations should first monitor their use of PowerDNS Recursor and identify if version 5.3.0 is deployed. Since no official patch is currently available, administrators should consider temporary workarounds such as disabling or limiting the processing of DNS queries with qtype ANY, which are not commonly required for normal operations. Implementing rate limiting on DNS queries, especially for ANY types, can reduce the risk of triggering the assertion failure. Network-level protections such as firewall rules to restrict DNS traffic from untrusted sources and deploying DNS query filtering can also help. Monitoring DNS logs for unusual patterns, including repeated ANY queries or cache insertions, can provide early warning signs. Organizations should subscribe to PowerDNS security advisories to promptly apply patches once released. Additionally, deploying redundant DNS resolvers with different software can improve resilience against single points of failure. For critical infrastructure, consider isolating DNS resolvers from direct internet exposure and using DNSSEC validation to enhance overall DNS security posture.