CVE-2024-38091 is a high-severity vulnerability affecting Microsoft Windows 10 Version 1809, specifically version 10.0.17763.0. The vulnerability is categorized under CWE-166, which relates to improper handling of missing special elements. In this case, the flaw resides in the WS-Discovery service, a network protocol used by Windows to discover services on a local network. The vulnerability allows an unauthenticated attacker to cause a denial of service (DoS) condition remotely by sending specially crafted WS-Discovery messages that exploit the improper handling of missing special elements within the protocol's processing logic. This leads to a crash or unavailability of the WS-Discovery service or potentially the entire system, impacting availability. The CVSS 3.1 base score is 7.5, indicating a high severity level, with an attack vector of network (AV:N), low attack complexity (AC:L), no privileges required (PR:N), and no user interaction needed (UI:N). The scope is unchanged (S:U), and the impact is limited to availability (A:H) with no confidentiality or integrity impact. The exploitability is officially unknown in the wild, and no patches or mitigations have been linked yet, though Microsoft is aware and has published the vulnerability details. This vulnerability is significant because WS-Discovery is widely used in Windows environments for network service discovery, and disruption can affect network operations and dependent applications or services.

For European organizations, the impact of this vulnerability can be substantial, especially for enterprises and public sector entities relying on Windows 10 Version 1809 in their infrastructure. The denial of service can disrupt critical network services that depend on WS-Discovery, such as device discovery, network printing, and other service advertisements. This disruption can lead to operational downtime, reduced productivity, and potential cascading failures in network-dependent applications. Since the vulnerability requires no authentication or user interaction, it can be exploited remotely by attackers on the same network or potentially from external networks if WS-Discovery traffic is exposed. This raises concerns for organizations with less segmented or poorly secured internal networks. Additionally, the lack of confidentiality or integrity impact means data theft or manipulation is unlikely, but availability loss can still cause significant business interruptions. Organizations in sectors like manufacturing, healthcare, finance, and government, which often rely on legacy Windows 10 systems, may face increased risk. The absence of known exploits in the wild currently reduces immediate risk but does not eliminate the threat, especially as attackers may develop exploits following public disclosure.

Given the absence of an official patch at the time of this report, European organizations should implement specific mitigations to reduce exposure. First, network segmentation should be enforced to isolate systems running Windows 10 Version 1809 from untrusted networks and limit WS-Discovery traffic to trusted segments only. Firewalls and network access controls should block WS-Discovery multicast traffic (UDP port 3702) from untrusted sources. Monitoring network traffic for unusual WS-Discovery requests can help detect exploitation attempts. Organizations should also prioritize upgrading affected systems to a supported and patched Windows version as soon as updates become available. If upgrading immediately is not feasible, consider disabling WS-Discovery service on systems where it is not essential, understanding this may impact network functionality. Additionally, applying strict endpoint protection and intrusion detection systems tuned to detect anomalous WS-Discovery activity can provide early warning. Finally, maintain awareness of Microsoft advisories for patches or workarounds and test them promptly in controlled environments before deployment.