CVE-2025-27483 is a high-severity vulnerability classified as CWE-125 (Out-of-bounds Read) affecting Microsoft Windows 10 Version 1809 (build 10.0.17763.0). This vulnerability arises from an out-of-bounds read condition within the Windows NTFS file system driver. Specifically, the flaw allows an unauthorized local attacker to read memory outside the intended buffer boundaries. This memory disclosure can lead to elevation of privileges by enabling the attacker to access sensitive kernel memory or data structures, potentially bypassing security controls. The vulnerability requires local access and some user interaction but does not require prior privileges (PR:N) and has low attack complexity (AC:L). The CVSS v3.1 base score is 7.8, reflecting high impact on confidentiality, integrity, and availability (all rated high). The scope is unchanged (S:U), meaning the vulnerability affects the same security scope. No known exploits are currently reported in the wild, and no official patches have been linked yet. The vulnerability was reserved in February 2025 and published in April 2025. The out-of-bounds read in NTFS is critical because NTFS is a core component of Windows file system operations, and exploitation could allow attackers to execute arbitrary code or escalate privileges locally, compromising system integrity and confidentiality.

For European organizations, this vulnerability poses a significant risk, especially those relying on Windows 10 Version 1809 in their infrastructure. Privilege escalation vulnerabilities can be leveraged by attackers who have gained limited access (e.g., via phishing or compromised user accounts) to gain full control over affected systems. This can lead to unauthorized access to sensitive data, disruption of critical services, and lateral movement within networks. Organizations in sectors such as finance, healthcare, government, and critical infrastructure are particularly at risk due to the sensitive nature of their data and regulatory requirements under GDPR and other frameworks. The lack of a patch increases the window of exposure, and although no exploits are known in the wild yet, the vulnerability's characteristics make it a likely target for attackers to develop exploits. Additionally, the requirement for local access means that insider threats or attackers who have already penetrated perimeter defenses could escalate privileges rapidly, undermining endpoint security.

Given the absence of an official patch, European organizations should implement several specific mitigations: 1) Restrict and monitor local user access, especially on systems running Windows 10 Version 1809, to minimize opportunities for attackers to exploit the vulnerability. 2) Employ application whitelisting and endpoint detection and response (EDR) solutions to detect anomalous behavior indicative of privilege escalation attempts. 3) Enforce the principle of least privilege rigorously, ensuring users operate with minimal necessary rights. 4) Disable or restrict NTFS features or services where feasible, particularly on systems not requiring full NTFS functionality. 5) Maintain strict control over removable media and network shares to reduce attack vectors for local exploitation. 6) Prepare for rapid deployment of patches once available by maintaining an up-to-date asset inventory and patch management process. 7) Conduct user awareness training to reduce the risk of initial compromise that could lead to local exploitation. 8) Monitor system logs for unusual access patterns or errors related to NTFS operations that might indicate exploitation attempts.