CVE-2025-21404 is a vulnerability classified under CWE-449 (Improper Use of a Dangerous Function) and CWE-451 (User Interface Misrepresentation) affecting Microsoft Edge (Chromium-based) version 1.0.0. The vulnerability arises because the browser's user interface performs an incorrect action, which can mislead users into executing unintended operations. This spoofing vulnerability does not compromise confidentiality or availability but impacts integrity by potentially causing users to perform actions they did not intend, such as clicking malicious links or approving harmful prompts. The CVSS 3.1 score is 4.3 (medium), with an attack vector of network (AV:N), low attack complexity (AC:L), no privileges required (PR:N), but requiring user interaction (UI:R). The scope remains unchanged (S:U), and the impact is limited to integrity (I:L) with no confidentiality or availability impact. There are no known exploits in the wild, and no patches have been released yet. The vulnerability was reserved in December 2024 and published in February 2025. The lack of patches means organizations must rely on interim mitigations and user awareness until an official fix is available.

For European organizations, this vulnerability poses a risk primarily through social engineering and phishing attacks that exploit the UI spoofing to trick users into performing unintended actions, potentially leading to credential theft, unauthorized transactions, or installation of malware. While the direct technical impact is limited to integrity, the indirect consequences could be significant depending on the targeted user’s role and access level. Organizations in sectors with high reliance on Microsoft Edge, such as finance, government, and critical infrastructure, may face increased risk. The absence of confidentiality and availability impact reduces the risk of data breaches or service disruptions directly caused by this flaw. However, the user interaction requirement means that effective user training and awareness are critical to reducing exploitation likelihood.

1. Educate users about the risk of UI spoofing and encourage vigilance when interacting with browser prompts or unusual UI elements. 2. Temporarily disable or restrict features in Microsoft Edge that allow automatic or unexpected UI actions, such as auto-approval dialogs or extensions with UI control, until a patch is released. 3. Employ endpoint protection solutions that can detect and block phishing and social engineering attempts leveraging UI spoofing. 4. Monitor official Microsoft security advisories closely and prioritize patching as soon as updates addressing CVE-2025-21404 become available. 5. Implement multi-factor authentication (MFA) to reduce the impact of potential credential theft resulting from spoofing attacks. 6. Use browser security policies via group policy or enterprise management tools to limit risky behaviors and enforce safe browsing practices. 7. Conduct simulated phishing exercises to improve user awareness and response to spoofing attempts.