CVE-2025-9491 is a high-severity vulnerability affecting Microsoft Windows, specifically the handling of .LNK (shortcut) files in Windows 11 Enterprise 23H2 (build 22631.4169 x64). The vulnerability is classified under CWE-451, which relates to User Interface (UI) Misrepresentation of Critical Information. The flaw allows crafted .LNK files to misrepresent hazardous content by making malicious elements invisible or misleading when viewed through the Windows UI. This misrepresentation can deceive users into opening or interacting with malicious shortcuts, enabling remote attackers to execute arbitrary code with the privileges of the current user. Exploitation requires user interaction, such as visiting a malicious webpage or opening a malicious file containing the crafted .LNK. The vulnerability does not require prior authentication but demands user action, which is a common attack vector for social engineering. The CVSS v3.0 base score is 7.0, indicating high severity, with vector metrics AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H, meaning the attack requires local access (e.g., user opening the file), high attack complexity, no privileges required, user interaction required, unchanged scope, and high impact on confidentiality, integrity, and availability. No known exploits in the wild have been reported yet, and no patches are currently linked, suggesting this is a recently disclosed vulnerability. The vulnerability was assigned by the Zero Day Initiative (ZDI) and published on August 26, 2025.

For European organizations, this vulnerability poses a significant risk, especially in environments where Windows 11 Enterprise 23H2 is deployed. Successful exploitation could lead to arbitrary code execution, enabling attackers to compromise user accounts, steal sensitive data, deploy malware, or disrupt operations. The UI misrepresentation aspect increases the likelihood of successful social engineering attacks, as users may be deceived into opening malicious shortcuts without suspicion. This can lead to lateral movement within corporate networks if attackers gain footholds on endpoint devices. Confidentiality, integrity, and availability of critical systems and data are at risk. Given the high impact on all three security pillars and the widespread use of Windows in European enterprises, the threat could affect sectors such as finance, government, healthcare, and critical infrastructure. The requirement for user interaction means phishing campaigns or malicious file distribution remain the primary attack vectors, which are common in targeted attacks and broad campaigns alike.

European organizations should implement targeted mitigations beyond generic advice: 1) Educate users specifically about the risks of opening unknown or unexpected shortcut (.LNK) files, emphasizing the possibility of UI misrepresentation. 2) Employ application whitelisting or restrict execution of .LNK files from untrusted sources or network shares. 3) Use endpoint detection and response (EDR) tools to monitor for suspicious activity related to .LNK file execution or unusual process spawning. 4) Implement network segmentation to limit the impact of compromised endpoints. 5) Enforce strict email filtering and attachment scanning to block malicious .LNK files. 6) Regularly audit and update Windows systems to the latest builds and patches as soon as Microsoft releases a fix. 7) Consider disabling the display or execution of .LNK files in environments where they are not necessary. 8) Use sandboxing or virtual desktop infrastructure (VDI) to isolate risky user activities. These steps, combined with continuous monitoring, will reduce the attack surface and improve detection and response capabilities.