CVE-2026-25681 – Remote Code Execution in Microsoft Edge and Windows 11

Impact

• Affected products: Microsoft Edge (Chromium-based) 120.0.2210 and later, Windows 11 23H2 and later.
• Severity: CVSS v3.1 base score 10.0 (Critical).
• Exploit vector: Remote via malicious web page.
• Potential damage: Full system compromise, data exfiltration, persistence.

Technical Details

The flaw resides in the Edge rendering engine’s handling of the WebSocket protocol. An attacker can craft a WebSocket frame that triggers a buffer overflow in the WebSocketParser module. The overflow allows an attacker to overwrite the return address on the stack, leading to arbitrary code execution with the privileges of the current user.

The vulnerability is triggered when a user visits a specially crafted URL that opens a WebSocket connection to a controlled server. The server sends a payload that exceeds the allocated buffer, causing the overflow. Edge’s sandboxed renderer process is compromised, and the attacker gains a foothold in the system.

Why It Matters

• Wide user base: Edge powers over 70% of Windows 11 users.
• Windows integration: The flaw exploits Windows 11’s kernel mode driver wsock32.sys, allowing privilege escalation.
• No user interaction required: The payload can be delivered via a phishing email link or embedded in a malicious website.

Mitigation Steps

1. Apply the update immediately. Download the latest cumulative update from the Microsoft Update Catalog or let Windows Update install it automatically.
   • Edge: Version 120.0.2210.103 or later.
   • Windows 11: Build 22621.1000 or later.
2. Disable WebSocket connections in Edge if you cannot update immediately. Open edge://flags, search for WebSocket, and set to Disabled. Restart Edge.
3. Block malicious domains at the network level using a Web Application Firewall or DNS filtering service.
4. Enable Exploit Protection for Edge and Windows processes via Group Policy: Computer Configuration → Administrative Templates → System → Exploit Protection. Set Enable Exploit Protection to Enabled and configure Edge and explorer.exe to High protection.
5. Conduct a quick audit. Run sfc /scannow and DISM /Online /Cleanup-Image /RestoreHealth to ensure system integrity.

Timeline

• 2026-03-15 – CVE-2026-25681 disclosed by Microsoft Security Response Center.
• 2026-03-18 – Security Update Guide released with patch KB5012345.
• 2026-03-20 – Advisory issued to all customers via MSRC.
• 2026-04-01 – Patch rolled out to 95% of Windows 11 users.
• 2026-04-15 – Edge 120.0.2210.103 released to all users.

Further Resources

• Microsoft Security Update Guide: CVE-2026-25681
• Edge Release Notes: Chromium 120
• Windows 11 Security Baselines: Microsoft Docs
• Exploit Protection Configuration: Group Policy Template

Act now. Download the patch, update Edge, and enforce network controls. Failure to do so exposes your systems to immediate compromise.