CVE-2025-26669 is a high-severity vulnerability identified as an out-of-bounds read (CWE-125) in the Windows Routing and Remote Access Service (RRAS) component of Microsoft Windows 10 Version 1809 (build 10.0.17763.0). This vulnerability allows an unauthorized attacker to remotely disclose sensitive information over the network without requiring privileges but does require user interaction. The flaw arises from improper bounds checking in RRAS, which can be exploited by sending specially crafted network packets to the affected system. Successful exploitation results in the attacker reading memory outside the intended buffer boundaries, potentially leaking sensitive data such as authentication tokens, cryptographic keys, or other confidential information residing in memory. The CVSS v3.1 base score of 8.8 reflects the high impact on confidentiality, integrity, and availability, with network attack vector, low attack complexity, no privileges required, but user interaction needed. Although no known exploits are currently reported in the wild, the vulnerability's characteristics make it a significant risk, especially in environments where Windows 10 Version 1809 is still in use and RRAS is enabled. The absence of published patches at this time increases the urgency for mitigation and monitoring.

For European organizations, this vulnerability poses a substantial risk, particularly for enterprises and service providers relying on Windows 10 Version 1809 systems with RRAS enabled for VPN or routing services. The out-of-bounds read can lead to unauthorized disclosure of sensitive information, potentially exposing credentials, internal network details, or other confidential data. This can facilitate further attacks such as lateral movement, privilege escalation, or targeted espionage. Critical infrastructure operators, financial institutions, healthcare providers, and government agencies in Europe are especially at risk due to the sensitive nature of their data and regulatory requirements like GDPR. The requirement for user interaction somewhat limits mass exploitation but does not eliminate targeted attacks, especially spear-phishing or social engineering campaigns that could trick users into triggering the vulnerability. The high severity and network-based attack vector mean that attackers can exploit this remotely, increasing the threat surface for organizations with exposed RRAS services.

Given the lack of available patches, European organizations should implement immediate compensating controls. First, disable RRAS on Windows 10 Version 1809 systems where it is not strictly necessary to reduce the attack surface. For systems requiring RRAS, restrict network access to RRAS services using firewalls and network segmentation, limiting exposure to trusted networks only. Employ strict monitoring and logging of RRAS traffic to detect anomalous or suspicious activity indicative of exploitation attempts. Educate users about the risks of interacting with unsolicited network prompts or connections that could trigger the vulnerability. Additionally, plan and prioritize upgrading affected systems to a supported Windows version with security updates. Employ endpoint detection and response (EDR) solutions capable of identifying memory disclosure attempts or unusual RRAS behavior. Finally, maintain up-to-date backups and incident response plans to mitigate potential impacts if exploitation occurs.