CVE-2024-8418 is a high-severity vulnerability affecting Aardvark-dns versions 1.12.0 and 1.12.1. The flaw arises from the way the DNS server processes TCP DNS queries: it handles them serially rather than concurrently. An attacker can exploit this by establishing a TCP connection to the DNS server and keeping it open indefinitely. Because the server processes queries one at a time, this open connection effectively blocks the processing of other incoming DNS queries. As a result, legitimate DNS requests time out, causing denial of service (DoS) conditions. This uncontrolled resource consumption leads to service unavailability, disrupting normal DNS resolution and potentially impacting any dependent services or applications. The vulnerability does not affect confidentiality or integrity but severely impacts availability. The CVSS 3.1 score is 7.5 (high), reflecting the network attack vector, low attack complexity, no privileges or user interaction required, and a significant impact on availability. No known exploits are currently reported in the wild, but the simplicity of the attack vector suggests it could be weaponized easily once public details are widely known. No patches or vendor advisories are currently linked, indicating that mitigation may require configuration changes or updates once available.

For European organizations, the impact of CVE-2024-8418 can be significant, especially for enterprises and service providers relying on Aardvark-dns for DNS resolution. DNS is a critical infrastructure component; disruption can lead to widespread service outages, affecting internal network operations, web services, email, and other critical applications. Organizations in sectors such as finance, healthcare, telecommunications, and government are particularly vulnerable due to their reliance on continuous DNS availability. The DoS condition could be exploited by threat actors to cause operational downtime, disrupt business continuity, or as part of a larger multi-vector attack. Additionally, organizations with public-facing DNS services using Aardvark-dns may face increased risk of external attacks, potentially impacting customers and partners. The lack of authentication or user interaction needed for exploitation means that attackers can launch attacks remotely and anonymously, increasing the threat surface. The disruption could also affect cloud and hosting providers in Europe that use this DNS software, cascading the impact to multiple downstream customers.

Immediate mitigation should focus on limiting the impact of the vulnerability until a patch is available. Organizations should monitor network traffic for unusually long-lived TCP DNS connections and implement connection timeouts or limits on the DNS server or network devices such as firewalls and load balancers. Rate limiting TCP connections to the DNS server can help prevent resource exhaustion. Deploying DNS over UDP where possible can reduce exposure since the vulnerability specifically affects TCP query processing. Network segmentation and access controls should restrict DNS TCP query access to trusted clients only. Organizations should also prepare to update Aardvark-dns to a patched version once released. In the interim, consider deploying alternative DNS servers or failover mechanisms to maintain DNS availability. Logging and alerting on DNS service anomalies will aid in early detection of exploitation attempts. Finally, coordinate with upstream providers and peers to share threat intelligence and mitigation strategies.