CVE-2025-21288 is a vulnerability identified in Microsoft Windows 10 Version 1809 (build 10.0.17763.0) involving the Windows Component Object Model (COM) server. The vulnerability is classified under CWE-908, which pertains to the use of uninitialized resources. Specifically, this flaw allows for information disclosure due to improper initialization of resources within the COM server component. An attacker with low privileges (local access) can exploit this vulnerability without requiring user interaction. The vulnerability has a CVSS v3.1 base score of 6.5, indicating a medium severity level. The attack vector is local (AV:L), with low attack complexity (AC:L), requiring privileges (PR:L) but no user interaction (UI:N). The scope is changed (S:C), meaning the vulnerability can affect resources beyond the initially vulnerable component. The impact is high on confidentiality (C:H), with no impact on integrity (I:N) or availability (A:N). No known exploits are currently reported in the wild, and no patches have been linked yet. The vulnerability could allow an attacker to gain unauthorized access to sensitive information residing in memory or other resources managed by the COM server, potentially leading to data leakage or further privilege escalation attempts if combined with other vulnerabilities.

For European organizations, this vulnerability poses a risk primarily to systems still running Windows 10 Version 1809, which is an older release. Organizations in sectors with legacy infrastructure or slower update cycles—such as government agencies, critical infrastructure, and certain industrial environments—may be more exposed. The information disclosure could lead to leakage of sensitive data, including credentials or configuration details, which could be leveraged for further attacks. Although the vulnerability does not directly impact system integrity or availability, the confidentiality breach could undermine trust, compliance with data protection regulations such as GDPR, and potentially expose organizations to targeted attacks. The requirement for local access and privileges limits remote exploitation but insider threats or compromised user accounts could still exploit this vulnerability. The lack of user interaction requirement increases the risk in automated or unattended environments.

Given the absence of an official patch at this time, European organizations should prioritize the following mitigations: 1) Identify and inventory all systems running Windows 10 Version 1809 and assess their criticality. 2) Apply any available security updates or workarounds from Microsoft as soon as they are released. 3) Restrict local access to sensitive systems by enforcing strict access control policies and monitoring for unauthorized privilege escalations. 4) Employ endpoint detection and response (EDR) solutions to detect anomalous behavior indicative of exploitation attempts. 5) Harden COM server configurations where possible, including disabling unnecessary COM components or services. 6) Educate users and administrators about the risks of privilege misuse and insider threats. 7) Plan and execute upgrades to newer, supported Windows versions to reduce exposure to legacy vulnerabilities. 8) Implement strict network segmentation to limit lateral movement from compromised accounts or systems.