CVE-2025-49757 is a high-severity heap-based buffer overflow vulnerability identified in the Windows Routing and Remote Access Service (RRAS) component of Microsoft Windows Server 2019 (version 10.0.17763.0). This vulnerability arises due to improper handling of memory buffers in RRAS, which is responsible for routing network traffic and providing remote access capabilities. An attacker who can send specially crafted network packets to a vulnerable server can trigger this overflow condition, leading to arbitrary code execution in the context of the system. The vulnerability requires no prior authentication (PR:N) but does require user interaction (UI:R), indicating that some form of user action, such as accepting a connection or interacting with the service, is necessary for exploitation. The attack vector is network-based (AV:N), meaning the attacker can exploit this remotely without physical or local access. The CVSS v3.1 base score is 8.8, reflecting high impact on confidentiality, integrity, and availability (all rated high), with low attack complexity and no privileges required. The scope remains unchanged (S:U), so the impact is limited to the vulnerable component. Although no known exploits are currently reported in the wild, the severity and nature of the vulnerability make it a critical concern for organizations running Windows Server 2019 with RRAS enabled. Exploitation could allow attackers to execute arbitrary code remotely, potentially leading to full system compromise, data breaches, or disruption of network services.

For European organizations, this vulnerability poses significant risks, especially for enterprises and service providers relying on Windows Server 2019 for routing and remote access services. Successful exploitation could lead to unauthorized access to sensitive data, disruption of critical network infrastructure, and potential lateral movement within corporate networks. This is particularly concerning for sectors with stringent data protection requirements such as finance, healthcare, and government institutions. The ability to execute arbitrary code remotely without authentication increases the likelihood of targeted attacks or automated exploitation attempts once a public exploit becomes available. Additionally, disruption of RRAS could impact business continuity by interrupting VPN services or remote access capabilities, which are vital for remote work scenarios prevalent in Europe. The high confidentiality, integrity, and availability impacts underscore the potential for data exfiltration, system manipulation, and denial of service conditions.

Organizations should immediately assess their exposure by identifying Windows Server 2019 instances running RRAS, especially version 10.0.17763.0. Since no patch links are currently provided, it is critical to monitor Microsoft security advisories for official updates and apply patches as soon as they become available. In the interim, organizations should consider disabling RRAS if it is not essential or restrict access to the service using network segmentation and firewall rules to limit exposure to trusted IP addresses only. Employing intrusion detection and prevention systems (IDS/IPS) with updated signatures to detect anomalous RRAS traffic can help identify exploitation attempts. Additionally, enforcing strict user interaction policies and educating users about suspicious network prompts can reduce the risk posed by the required user interaction. Regularly auditing and hardening server configurations, applying the principle of least privilege, and maintaining up-to-date backups will also help mitigate potential damage from exploitation.