CVE-2025-30394 is a medium-severity vulnerability identified in Microsoft Windows Server 2019, specifically affecting version 10.0.17763.0. The flaw is categorized under CWE-591, which involves sensitive data storage in improperly locked memory. This vulnerability resides in the Remote Desktop Gateway Service, a critical component that facilitates secure remote access to internal network resources. The issue arises because sensitive data is stored in memory regions that are not properly locked, potentially allowing unauthorized attackers to exploit this weakness to cause a denial of service (DoS) over the network. The CVSS 3.1 base score is 5.9, reflecting a medium severity level. The attack vector is network-based (AV:N), requiring no privileges (PR:N) and no user interaction (UI:N), but with high attack complexity (AC:H). The impact is limited to availability (A:H), with no confidentiality or integrity impact. The vulnerability does not currently have known exploits in the wild, and no patches have been linked yet. However, the improper memory locking could allow attackers to disrupt Remote Desktop Gateway operations, potentially causing service outages and impacting business continuity. Since Remote Desktop Gateway is often used to provide secure remote access, its disruption can significantly affect remote work capabilities and access to critical systems.

For European organizations, the impact of this vulnerability can be significant, especially for those relying heavily on Windows Server 2019 Remote Desktop Gateway for remote access and business continuity. A successful denial of service attack could disrupt remote connectivity, affecting employees working remotely or accessing internal resources from outside the corporate network. This could lead to operational downtime, loss of productivity, and potential financial losses. While the vulnerability does not expose sensitive data directly or allow unauthorized data modification, the availability impact can indirectly affect confidentiality and integrity by forcing fallback to less secure access methods or causing delays in critical operations. Organizations in sectors such as finance, healthcare, government, and critical infrastructure, which often use Remote Desktop Gateway for secure remote access, may face heightened risks. Additionally, the high attack complexity reduces the likelihood of widespread exploitation but does not eliminate targeted attacks by skilled adversaries.

Given the absence of an official patch at this time, European organizations should implement specific mitigations to reduce exposure. First, restrict network access to the Remote Desktop Gateway service using network segmentation and firewall rules, allowing connections only from trusted IP ranges and VPNs. Second, monitor Remote Desktop Gateway logs and network traffic for unusual patterns that may indicate exploitation attempts or denial of service activity. Third, consider deploying rate limiting and connection throttling on the Remote Desktop Gateway to mitigate potential DoS impacts. Fourth, ensure that all Windows Server 2019 instances are fully updated with the latest security patches and cumulative updates, as Microsoft may release a fix soon. Fifth, evaluate alternative remote access solutions or failover mechanisms to maintain business continuity if the Remote Desktop Gateway service is disrupted. Finally, maintain robust incident response plans to quickly detect and respond to any service disruptions related to this vulnerability.