CVE-2025-55692 is a vulnerability classified under CWE-20 (Improper Input Validation) affecting Microsoft Windows 11 Version 25H2, specifically build 10.0.26200.0. The flaw resides in the Windows Error Reporting (WER) component, which is responsible for collecting and reporting error data to Microsoft. Improper validation of input data within WER allows an attacker with local authorized access to manipulate the error reporting process to elevate their privileges on the system. This elevation of privilege (EoP) can enable the attacker to execute code or commands with higher privileges than initially granted, potentially leading to full system compromise. The CVSS v3.1 base score is 7.8, indicating a high severity level. The vector metrics specify that the attack requires local access (AV:L), low attack complexity (AC:L), and privileges (PR:L) but no user interaction (UI:N). The scope remains unchanged (S:U), but the impact on confidentiality, integrity, and availability is high (C:H/I:H/A:H). No known exploits have been reported in the wild yet, but the vulnerability's nature makes it a critical concern for organizations relying on Windows 11 25H2. The lack of an official patch at the time of publication necessitates proactive mitigation strategies. This vulnerability highlights the risks posed by insufficient input validation in critical OS components that handle system diagnostics and error reporting.

For European organizations, this vulnerability poses a significant risk due to the widespread use of Windows 11 25H2 in enterprise environments. Successful exploitation could allow attackers with local access—such as malicious insiders or attackers who have gained initial footholds—to escalate privileges and gain control over affected systems. This can lead to unauthorized access to sensitive data, disruption of critical services, and potential lateral movement within networks. Sectors such as finance, healthcare, government, and critical infrastructure are particularly vulnerable due to their reliance on Windows endpoints and the sensitive nature of their data. The high impact on confidentiality, integrity, and availability means that exploitation could result in data breaches, operational downtime, and regulatory non-compliance under GDPR and other European data protection laws. Additionally, the lack of user interaction required for exploitation increases the risk of automated or stealthy attacks once local access is obtained.

1. Apply official Microsoft patches immediately once they become available for Windows 11 Version 25H2 build 10.0.26200.0. 2. Until patches are released, restrict local access to critical systems by enforcing strict access controls and limiting administrative privileges. 3. Implement application whitelisting and endpoint detection and response (EDR) solutions to monitor and block suspicious activities related to Windows Error Reporting processes. 4. Conduct regular audits of user privileges and remove unnecessary local administrator rights to minimize the attack surface. 5. Employ network segmentation to isolate critical systems and reduce the risk of lateral movement following privilege escalation. 6. Monitor system logs and Windows Event Logs for anomalies related to error reporting and privilege escalation attempts. 7. Educate IT staff and users about the risks of local privilege escalation vulnerabilities and the importance of reporting unusual system behavior. 8. Consider deploying host-based intrusion prevention systems (HIPS) that can detect exploitation attempts targeting input validation flaws.