CVE-2025-59284 is a vulnerability identified in Microsoft Windows 11 version 22H2 (build 10.0.22621.0) that results in the exposure of sensitive information to unauthorized actors via the NTLM authentication protocol. The vulnerability is classified under CWE-200, indicating an information exposure issue. Specifically, it allows a local attacker to perform spoofing attacks by exploiting the way NTLM handles authentication data, potentially gaining unauthorized access to sensitive information. The attack vector requires local access (AV:L), low attack complexity (AC:L), no privileges required (PR:N), but user interaction is necessary (UI:R). The scope remains unchanged (S:U), and the impact is limited to confidentiality (C:L) with no impact on integrity or availability. The CVSS v3.1 base score is 3.3, reflecting a low severity rating. No known exploits have been reported in the wild, and no official patches have been released at the time of publication. The vulnerability could be leveraged in environments where local users or malicious insiders have access to Windows 11 systems, potentially enabling them to spoof identities or extract sensitive authentication data. This flaw highlights the ongoing risks associated with NTLM, an older authentication protocol still present in modern Windows environments.

For European organizations, the exposure of sensitive information via NTLM spoofing could lead to unauthorized access to internal resources or credential theft, especially in environments where local user access is not tightly controlled. Although the vulnerability does not directly compromise system integrity or availability, the leakage of authentication data could facilitate lateral movement or privilege escalation in multi-user or enterprise settings. Organizations with extensive Windows 11 deployments, particularly in sectors like finance, healthcare, and critical infrastructure, may face increased risk if attackers exploit this flaw to gather intelligence or impersonate legitimate users. The requirement for local access and user interaction limits remote exploitation, but insider threats or compromised endpoints could still leverage this vulnerability. The absence of known exploits reduces immediate risk, but the potential for future exploitation necessitates proactive measures.

To mitigate CVE-2025-59284, European organizations should implement strict local access controls, ensuring that only trusted users have physical or remote desktop access to Windows 11 systems. Monitoring and logging NTLM authentication traffic can help detect anomalous spoofing attempts. Disabling or restricting NTLM usage where possible, favoring more secure authentication protocols like Kerberos, will reduce exposure. Applying least privilege principles and segmenting networks to limit lateral movement can contain potential exploitation. Organizations should stay alert for official patches or updates from Microsoft and prioritize their deployment once available. Additionally, educating users about the risks of interacting with suspicious prompts can reduce the likelihood of successful user-interaction-dependent attacks. Employing endpoint detection and response (EDR) solutions capable of identifying NTLM spoofing behaviors can further enhance defense.