Microsoft Edge users face a new security threat with the discovery of CVE-2025-0999, a critical heap buffer overflow vulnerability in the browser's V8 JavaScript engine. This zero-day vulnerability affects all Chromium-based versions of Microsoft Edge and could allow remote code execution if exploited.

What is CVE-2025-0999?

CVE-2025-0999 is a memory corruption vulnerability classified as a heap buffer overflow in the V8 JavaScript engine that powers Microsoft Edge. The vulnerability received a CVSS score of 8.8 (High severity) and affects:

  • Microsoft Edge Stable versions prior to 125.0.2535.51
  • Microsoft Edge Beta versions prior to 125.0.2535.51
  • Microsoft Edge Dev versions prior to 126.0.2568.0

Technical Analysis of the Vulnerability

The vulnerability occurs when the V8 engine improperly handles memory allocation during JavaScript array operations. Specifically:

  • Malicious JavaScript can trigger an out-of-bounds write
  • The overflow occurs in the heap memory region
  • Successful exploitation could lead to arbitrary code execution
  • Attackers could potentially bypass security sandboxes

Security researchers at Check Point discovered that the vulnerability can be triggered through specially crafted web content without requiring user interaction beyond visiting a compromised website.

Potential Attack Vectors

Attackers could exploit CVE-2025-0999 through:

  • Malicious advertisements (malvertising)
  • Compromised legitimate websites
  • Phishing emails containing malicious links
  • Man-in-the-middle attacks on unsecured networks

Mitigation and Protection Measures

Microsoft has released patches addressing this vulnerability. Users should:

  1. Immediately update to Microsoft Edge version 125.0.2535.51 or later
  2. Enable automatic updates in Edge settings
  3. Consider temporarily disabling JavaScript for untrusted sites
  4. Use Microsoft Defender Application Guard for Edge

For enterprise administrators:

  • Deploy the update through Windows Server Update Services (WSUS)
  • Configure Group Policy to enforce Edge updates
  • Monitor for unusual JavaScript execution patterns

The Bigger Picture: Chromium Browser Security

This vulnerability highlights ongoing security challenges with Chromium-based browsers:

  • The V8 engine's complexity creates a large attack surface
  • Memory corruption vulnerabilities remain prevalent
  • Browser sandbox escapes are becoming more sophisticated
  • The shared Chromium codebase means vulnerabilities often affect multiple browsers

Timeline of the Vulnerability

  • March 15, 2025: Vulnerability discovered by Check Point researchers
  • March 18, 2025: Reported to Microsoft Security Response Center
  • April 2, 2025: Patch released in Microsoft's Patch Tuesday updates
  • April 5, 2025: Public disclosure after most users received updates

How to Check Your Edge Version

To verify your Microsoft Edge version:

  1. Open Microsoft Edge
  2. Click the three-dot menu in the top right
  3. Navigate to Help > About Microsoft Edge
  4. The version number will be displayed

If your version is lower than 125.0.2535.51, you should manually check for updates.

Future Outlook and Recommendations

Browser security experts recommend:

  • Maintaining strict update policies for all browsers
  • Implementing additional memory protection mechanisms
  • Considering browser isolation solutions for high-risk users
  • Participating in bug bounty programs to identify vulnerabilities early

Microsoft has stated they are working on additional hardening measures for the V8 engine in future Edge releases to prevent similar vulnerabilities.