CVE-2025-55692 is a vulnerability classified under CWE-20 (Improper Input Validation) affecting Microsoft Windows 11 Version 25H2 (build 10.0.26200.0). The flaw resides in the Windows Error Reporting (WER) mechanism, which is responsible for collecting and sending error reports to Microsoft. Improper validation of inputs within WER allows an attacker with authorized local access to manipulate the error reporting process to escalate their privileges on the system. The vulnerability does not require user interaction and has a low attack complexity, meaning an attacker with standard local privileges can exploit it without needing additional conditions. Successful exploitation could lead to full system compromise, including unauthorized access to sensitive data, modification of system files, and disruption of system availability. The CVSS v3.1 score of 7.8 reflects high severity, with high impact on confidentiality, integrity, and availability, and privileges required are low (local user). No public exploits or patches are currently available, but the vulnerability is published and should be addressed promptly once mitigations are released. This vulnerability is particularly critical because Windows 11 is widely deployed in enterprise environments, and local privilege escalation can be a stepping stone for attackers to gain persistent and elevated access.

For European organizations, this vulnerability poses a significant risk due to the widespread use of Windows 11 in corporate and governmental environments. Successful exploitation could allow attackers to bypass security controls, gain administrative privileges, and execute malicious code, potentially leading to data breaches, ransomware deployment, or disruption of critical services. The impact on confidentiality is high as attackers could access sensitive information; integrity is compromised through unauthorized system modifications; and availability could be affected by system instability or denial-of-service conditions. Organizations in sectors such as finance, healthcare, energy, and government are particularly vulnerable due to the critical nature of their operations and the value of their data. The local attack vector means that insider threats or attackers who have gained initial foothold via other means could leverage this vulnerability to escalate privileges and deepen their access. The absence of known exploits in the wild currently reduces immediate risk but does not diminish the urgency for remediation given the ease of exploitation and high impact.

1. Monitor Microsoft security advisories closely and apply official patches or updates as soon as they become available to remediate this vulnerability. 2. Implement strict local user privilege management by limiting the number of users with local access and ensuring the principle of least privilege is enforced. 3. Use application whitelisting and endpoint detection and response (EDR) solutions to detect and block suspicious activities related to privilege escalation attempts. 4. Regularly audit and monitor Windows Error Reporting logs and system event logs for unusual or unauthorized activities that could indicate exploitation attempts. 5. Employ network segmentation to restrict lateral movement from compromised local accounts. 6. Educate IT staff and users about the risks of local privilege escalation and the importance of reporting unusual system behavior. 7. Consider deploying enhanced security features available in Windows 11, such as virtualization-based security (VBS) and Credential Guard, to mitigate privilege escalation risks. 8. Restrict physical and remote access to systems to trusted personnel only, reducing the chance of local exploitation.