CVE-2025-33069 is a vulnerability identified in Microsoft Windows Server 2025, specifically affecting the Server Core installation version 10.0.26100.0. The flaw involves improper verification of cryptographic signatures within the App Control for Business (WDAC) feature. WDAC is a security mechanism designed to enforce code integrity policies by allowing only trusted applications to run, based on cryptographic signatures. The vulnerability arises from a weakness in the signature verification process, categorized under CWE-347 (Improper Verification of Cryptographic Signature). This flaw enables a local attacker without any privileges (no privileges required) and without user interaction to bypass the WDAC security controls. The attacker can exploit this to run unauthorized or malicious code that would normally be blocked by WDAC, potentially undermining the system's integrity and trust model. The CVSS v3.1 base score is 5.1 (medium severity), reflecting that the attack vector is local (AV:L), requires low attack complexity (AC:L), no privileges (PR:N), and no user interaction (UI:N). The impact affects confidentiality and integrity but not availability, and the scope remains unchanged (S:U). No known exploits are currently reported in the wild, and no patches have been linked yet, indicating that mitigation may rely on vendor updates or configuration changes once available. This vulnerability is significant because it targets a core security feature designed to prevent unauthorized code execution, which is critical in server environments where trust and integrity are paramount.

For European organizations, this vulnerability poses a moderate risk, particularly for enterprises and service providers relying on Windows Server 2025 Server Core installations with WDAC enabled. The ability for a local attacker to bypass WDAC could lead to unauthorized code execution, potentially allowing lateral movement within networks, privilege escalation, or deployment of persistent malware. Confidentiality and integrity of sensitive data could be compromised, especially in sectors with stringent data protection requirements such as finance, healthcare, and government. Although the attack requires local access, insider threats or attackers who have gained limited footholds could exploit this flaw to escalate their capabilities. The absence of user interaction and privileges required lowers the barrier for exploitation once local access is obtained. Given the critical role of Windows Server in enterprise infrastructure, this vulnerability could disrupt business operations and erode trust in security controls if exploited. However, the medium severity and lack of known exploits suggest that immediate widespread impact is unlikely but should not be underestimated in high-security environments.

European organizations should prioritize the following mitigation steps: 1) Monitor for official Microsoft security advisories and apply patches promptly once released for Windows Server 2025 Server Core installations. 2) Restrict local access to servers running this version to trusted administrators only, employing strict access controls and network segmentation to minimize the risk of local exploitation. 3) Implement enhanced monitoring and logging for WDAC events and unusual application execution patterns to detect potential bypass attempts early. 4) Use complementary security controls such as endpoint detection and response (EDR) solutions that can identify anomalous behavior indicative of WDAC bypass. 5) Conduct regular security audits and penetration testing focused on local privilege escalation and code integrity bypass scenarios. 6) Consider deploying application whitelisting policies with additional verification layers or alternative integrity enforcement mechanisms until the vulnerability is patched. 7) Educate system administrators about the risks of local access and the importance of maintaining strict operational security on critical servers.