CVE-2024-26215 is a high-severity vulnerability affecting the DHCP Server component of Microsoft Windows Server 2019 (specifically version 10.0.17763.0). The vulnerability is categorized under CWE-400, which relates to uncontrolled resource consumption, commonly known as a denial-of-service (DoS) condition. This flaw allows an unauthenticated attacker to remotely exploit the DHCP Server service over the network without requiring user interaction. By sending specially crafted DHCP requests or packets, the attacker can trigger excessive resource consumption on the affected server, leading to service degradation or complete denial of DHCP services. The CVSS 3.1 base score of 7.5 reflects the high impact on availability, with no impact on confidentiality or integrity. The attack vector is network-based (AV:N), with low attack complexity (AC:L), no privileges required (PR:N), and no user interaction needed (UI:N). The scope remains unchanged (S:U), meaning the vulnerability affects only the DHCP Server component without impacting other system components. Exploit code is not currently known to be in the wild, but the vulnerability is publicly disclosed and could be targeted in the future. The lack of an available patch at the time of publication increases the urgency for mitigation and monitoring. This vulnerability could disrupt network operations by preventing DHCP from assigning IP addresses, which is critical for network connectivity and service availability in enterprise environments running Windows Server 2019 DHCP services.

For European organizations, this vulnerability poses a significant risk to network infrastructure stability and availability. Many enterprises, government agencies, and service providers across Europe rely on Windows Server 2019 for DHCP services to manage IP address allocation dynamically. A successful exploitation could lead to widespread denial of DHCP services, causing network outages, loss of connectivity for end devices, and disruption of business-critical applications. This is especially impactful for sectors with high dependency on continuous network availability such as finance, healthcare, telecommunications, and public administration. Additionally, the disruption of DHCP services could indirectly affect other network-dependent security controls and monitoring systems, potentially increasing the risk of further exploitation or operational failures. Given the vulnerability requires no authentication or user interaction, it can be exploited remotely by attackers with network access, increasing the attack surface. The absence of known exploits currently reduces immediate risk but does not eliminate the threat, especially as threat actors may develop exploits following public disclosure.

1. Immediate network-level controls: Implement firewall rules to restrict inbound DHCP traffic (UDP ports 67 and 68) to trusted network segments and known DHCP clients only, minimizing exposure to untrusted networks. 2. Network segmentation: Isolate DHCP servers within secure network zones with strict access controls to limit potential attack vectors. 3. Monitoring and alerting: Deploy network monitoring tools to detect abnormal DHCP traffic patterns indicative of resource exhaustion attempts, such as unusually high DHCP request rates or malformed packets. 4. Temporary service hardening: Where possible, configure DHCP server rate limiting or request filtering features to mitigate excessive request floods. 5. Patch management: Monitor Microsoft advisories closely and apply official patches or updates as soon as they become available. 6. Incident response readiness: Prepare response plans for DHCP service outages, including fallback static IP configurations or alternate DHCP servers to maintain network availability. 7. Vendor engagement: Engage with Microsoft support channels for any interim mitigations or hotfixes and report any suspicious activity related to DHCP services. These steps go beyond generic advice by focusing on network-level controls, proactive monitoring, and operational continuity planning specific to DHCP service availability.