CVE-2025-54111 is a high-severity use-after-free vulnerability identified in Microsoft Windows 10 Version 1809 (build 10.0.17763.0), specifically within the Windows UI XAML Phone DatePickerFlyout component. The vulnerability arises due to improper handling of memory, where a program continues to use a pointer after the memory it points to has been freed. This can lead to unpredictable behavior, including the possibility for an attacker to execute arbitrary code or escalate privileges. In this case, an authorized local attacker with low privileges (PR:L) but no user interaction required (UI:N) can exploit this flaw to elevate their privileges on the affected system. The vulnerability affects confidentiality, integrity, and availability, as indicated by the CVSS vector (C:H/I:H/A:H), and the scope is changed (S:C), meaning the vulnerability can affect resources beyond the initially vulnerable component. The attack complexity is high (AC:H), implying exploitation requires specific conditions or expertise. No known exploits are currently reported in the wild, and no patches have been linked yet. The vulnerability was reserved in mid-July 2025 and published in early September 2025, indicating recent discovery and disclosure. The use-after-free issue in a UI component suggests that exploitation might involve triggering specific UI interactions or system calls related to the DatePickerFlyout, potentially through crafted applications or scripts running locally. Given the affected version is Windows 10 1809, which is an older release, many organizations may have already moved to newer versions, but legacy systems remain at risk.

For European organizations, this vulnerability poses a significant risk, especially for those still operating legacy Windows 10 Version 1809 systems, which may be prevalent in industrial, governmental, or specialized environments where upgrading is slower. Successful exploitation allows local attackers to gain elevated privileges, potentially leading to full system compromise, unauthorized access to sensitive data, and disruption of critical services. This can impact confidentiality by exposing sensitive information, integrity by allowing unauthorized changes to system configurations or data, and availability by enabling denial-of-service conditions or persistent malware installation. The lack of required user interaction facilitates stealthy exploitation by insiders or malware that has already gained limited access. Given the high severity and scope change, the vulnerability could be leveraged as part of multi-stage attacks targeting critical infrastructure, financial institutions, or government agencies in Europe, where Windows 10 1809 remains in use. The absence of known exploits in the wild currently limits immediate risk but also suggests the need for proactive mitigation to prevent future exploitation.

European organizations should prioritize identifying and inventorying all systems running Windows 10 Version 1809 to assess exposure. Since no official patches are linked yet, organizations should monitor Microsoft’s security advisories closely for updates or emergency patches. In the interim, applying strict local access controls and minimizing the number of users with local access rights can reduce the risk of exploitation. Employ application whitelisting and endpoint detection and response (EDR) solutions to detect anomalous behavior related to privilege escalation attempts. Restrict or monitor usage of the Windows UI XAML Phone DatePickerFlyout component where possible, and consider disabling or limiting features that invoke this component if operationally feasible. Additionally, organizations should enforce the principle of least privilege, ensuring users operate with the minimum necessary permissions. Regularly updating to supported Windows versions beyond 1809 is strongly recommended to mitigate this and other legacy vulnerabilities. Conducting targeted penetration testing and vulnerability assessments focusing on local privilege escalation vectors can help identify exploitation attempts.