CVE-2025-53806 is a buffer over-read vulnerability classified under CWE-126 affecting Microsoft Windows Server 2019, specifically version 10.0.17763.0. The flaw exists in the Windows Routing and Remote Access Service (RRAS), a component that provides routing and VPN services. The vulnerability arises due to improper bounds checking when processing certain network inputs, allowing an attacker to read memory beyond the intended buffer boundaries. This can lead to unauthorized disclosure of sensitive information over the network without requiring authentication privileges. The CVSS v3.1 base score is 6.5, indicating a medium severity level, with an attack vector of network (AV:N), low attack complexity (AC:L), no privileges required (PR:N), but requiring user interaction (UI:R). The impact is limited to confidentiality (C:H), with no impact on integrity or availability. No known exploits have been reported in the wild, and no official patches have been released as of the publication date. The vulnerability could be exploited by sending specially crafted packets to the RRAS service, potentially leaking sensitive memory contents that could aid further attacks or reconnaissance. Given RRAS’s role in network routing and VPN connectivity, exploitation could expose sensitive network configuration or session data. The vulnerability is notable because it affects a widely deployed Microsoft server product used in enterprise and service provider environments.

For European organizations, the primary impact is the potential unauthorized disclosure of sensitive information from Windows Server 2019 systems running RRAS. This could include network configuration details, session tokens, or other memory-resident sensitive data that attackers could leverage for lateral movement or further attacks. Confidentiality breaches could affect regulated industries such as finance, healthcare, and critical infrastructure, leading to compliance violations under GDPR and other data protection laws. While the vulnerability does not allow direct code execution or denial of service, the information disclosure could facilitate more sophisticated attacks. Organizations with exposed RRAS services, especially those providing VPN or routing services to remote users or partners, are at higher risk. The medium severity rating reflects the balance between the ease of remote exploitation without privileges and the limited impact scope. However, the lack of patches and the potential for future exploit development necessitate proactive risk management.

1. Immediately assess and inventory all Windows Server 2019 systems running RRAS, focusing on version 10.0.17763.0. 2. Where possible, disable RRAS services if not required, or restrict RRAS exposure to trusted internal networks only. 3. Implement network-level filtering and firewall rules to block unsolicited or untrusted traffic to RRAS ports, reducing attack surface. 4. Monitor network traffic for anomalous or malformed packets targeting RRAS to detect potential exploitation attempts. 5. Prepare for rapid deployment of official patches once Microsoft releases updates addressing CVE-2025-53806. 6. Employ endpoint detection and response (EDR) tools to identify suspicious activity related to RRAS. 7. Educate network and security teams about this vulnerability to ensure timely incident response. 8. Consider segmentation of critical systems to limit lateral movement if information disclosure occurs. 9. Review and tighten VPN and remote access configurations to minimize unnecessary exposure. 10. Regularly review Microsoft security advisories for updates and mitigation guidance.