CVE-2025-27475 is a high-severity vulnerability identified in Microsoft Windows 11 version 22H2 (build 10.0.22621.0) related to improper handling of sensitive data in memory within the Windows Update Stack. Specifically, the vulnerability arises from sensitive data being stored in memory that is not properly locked, allowing an authorized local attacker with low privileges to elevate their privileges. The underlying weakness is classified under CWE-591, which concerns sensitive data storage in improperly locked memory regions. This improper locking means that sensitive information, such as authentication tokens or cryptographic keys, could be exposed to other processes or users on the same system, potentially allowing privilege escalation. The CVSS v3.1 score of 7.0 reflects a high severity, with the vector indicating local attack vector (AV:L), high attack complexity (AC:H), low privileges required (PR:L), no user interaction (UI:N), unchanged scope (S:U), and high impact on confidentiality, integrity, and availability (C:H/I:H/A:H). No known exploits are currently reported in the wild, and no patches have been linked yet, indicating that mitigation may rely on forthcoming updates from Microsoft. The vulnerability requires local access but no user interaction, making it a significant risk for environments where multiple users or processes share the same machine, such as enterprise desktops or servers running Windows 11 22H2. Attackers exploiting this flaw could gain elevated privileges, potentially leading to full system compromise or unauthorized access to sensitive data and system functions.

For European organizations, this vulnerability poses a substantial risk, especially in sectors relying heavily on Windows 11 22H2 deployments, such as finance, healthcare, government, and critical infrastructure. The ability for a low-privileged local attacker to escalate privileges could lead to unauthorized access to sensitive corporate or personal data, disruption of services, and potential lateral movement within networks. Given the high impact on confidentiality, integrity, and availability, exploitation could result in data breaches, operational downtime, and regulatory non-compliance under frameworks like GDPR. Organizations with shared workstation environments or those using Windows 11 in virtualized or terminal server setups are particularly vulnerable. The absence of known exploits currently provides a window for proactive mitigation, but the high severity score underscores the urgency of addressing this vulnerability to prevent potential exploitation, especially as threat actors often develop exploits rapidly after disclosure.

European organizations should implement a multi-layered approach to mitigate this vulnerability effectively. First, monitor Microsoft security advisories closely and prioritize deployment of official patches or updates as soon as they become available. Until patches are released, restrict local access to Windows 11 22H2 systems by enforcing strict access controls and limiting user privileges to the minimum necessary. Employ application whitelisting and endpoint detection and response (EDR) solutions to detect and block suspicious privilege escalation attempts. Conduct regular audits of user accounts and permissions to identify and remove unnecessary local accounts or elevated privileges. Additionally, consider isolating critical systems or using virtualization-based security features available in Windows 11 to reduce the attack surface. Educate IT staff and users about the risks of local privilege escalation and enforce policies that prevent installation of unauthorized software or execution of untrusted code. Finally, implement robust logging and monitoring to detect anomalous activities indicative of exploitation attempts.