CVE-2025-55681 is an out-of-bounds read vulnerability identified in the Desktop Window Manager (DWM) component of Microsoft Windows 11 Version 25H2 (build 10.0.26200.0). The flaw arises from improper bounds checking in memory operations, allowing an attacker with authorized local access and limited privileges to read memory beyond intended boundaries. This memory corruption can be leveraged to elevate privileges on the affected system, granting the attacker higher-level access than originally permitted. The vulnerability does not require user interaction but does require local access with some privileges (low privileges). The CVSS v3.1 base score is 7.0, reflecting high severity due to its impact on confidentiality, integrity, and availability, combined with the complexity of exploitation (high attack complexity) and the need for local privileges. No public exploits or patches are currently available, indicating the vulnerability is newly disclosed. The vulnerability is tracked under CWE-125 (Out-of-bounds Read), which typically leads to information disclosure or memory corruption, and can be a stepping stone for privilege escalation. The absence of patches necessitates proactive mitigation until official updates are released by Microsoft.

For European organizations, this vulnerability poses a significant risk, especially in environments where Windows 11 Version 25H2 is deployed on critical endpoints or servers. Successful exploitation could allow attackers to escalate privileges locally, potentially leading to unauthorized access to sensitive data, disruption of services, or further lateral movement within networks. This is particularly concerning for sectors such as finance, healthcare, government, and critical infrastructure, where confidentiality and integrity of data are paramount. The requirement for local access limits remote exploitation but does not eliminate risk, as insider threats or compromised low-privilege accounts could exploit this flaw. The lack of current exploits reduces immediate risk but also means organizations must be vigilant and prepared for potential future attacks once exploit code becomes available. The vulnerability could also impact availability if attackers leverage elevated privileges to disrupt system operations.

Until Microsoft releases an official patch, European organizations should implement the following specific mitigations: 1) Enforce strict local access controls by limiting user accounts with local login privileges, especially on sensitive systems. 2) Apply the principle of least privilege rigorously to reduce the number of accounts with low-level privileges that could be leveraged. 3) Monitor system logs and use endpoint detection and response (EDR) tools to identify unusual local activity indicative of privilege escalation attempts. 4) Disable or restrict access to the Desktop Window Manager service where feasible, particularly on servers or critical systems that do not require graphical interfaces. 5) Employ application whitelisting and integrity monitoring to detect unauthorized changes or suspicious processes. 6) Prepare for rapid deployment of Microsoft patches by maintaining up-to-date asset inventories and testing environments. 7) Educate internal users about the risks of local exploitation and enforce strong authentication and session management policies to prevent unauthorized local access.