KB5078738 — Cumulative Security Update for Internet Explorer

Overview

KB5078738 is a cumulative security update released on March 10, 2026, that addresses multiple critical vulnerabilities in Internet Explorer. This update applies to Windows Server 2012 and Windows Server 2012 R2 systems, including Server Core installations. The update resolves remote code execution, information disclosure, and security feature bypass vulnerabilities that could be exploited by attackers through malicious web content.

Affected Systems

This security update applies to the following operating systems:

Security Vulnerabilities Addressed

This cumulative update addresses multiple security vulnerabilities in Internet Explorer components:

Remote Code Execution Vulnerabilities

The update fixes several memory corruption vulnerabilities in the Internet Explorer scripting engine that could allow remote code execution. These vulnerabilities affect the JavaScript and VBScript engines and could be exploited when users visit specially crafted websites or open malicious documents.

Information Disclosure Vulnerabilities

Multiple information disclosure vulnerabilities in URL validation and cross-origin resource sharing have been resolved. These vulnerabilities could allow attackers to access sensitive information from other domains or bypass same-origin policy restrictions.

Security Feature Bypass Vulnerabilities

The update addresses vulnerabilities that could allow attackers to bypass Internet Explorer security zone restrictions and execute code with elevated privileges. These vulnerabilities affect the security zone enforcement mechanisms and ActiveX control policies.

Use-After-Free Vulnerabilities

Several use-after-free vulnerabilities in DOM handling have been fixed. These vulnerabilities could lead to remote code execution when processing malicious web content that manipulates DOM objects in specific ways.

Installation Requirements

Before installing KB5078738, ensure the following requirements are met:

• Administrative Privileges: Installation requires local administrator rights
• Disk Space: Minimum 50 MB of free disk space recommended
• Network Connectivity: Required for automatic installation via Windows Update
• System Resources: Sufficient system resources to complete the installation process

Deployment Considerations

For enterprise environments, consider the following deployment strategies:

Windows Server Update Services (WSUS)

Administrators can deploy this update through WSUS by approving it for the appropriate computer groups. The update will appear in the Security Updates classification.

System Center Configuration Manager (SCCM)

Deploy the update through SCCM software update management by creating a deployment package and targeting the appropriate device collections.

Group Policy

Configure automatic update policies through Group Policy to ensure consistent deployment across the organization.

Post-Installation Verification

After installing KB5078738, verify the installation using the following methods:

Command Line Verification

Get-HotFix -Id KB5078738

Registry Verification

Check the following registry location for the installed update:

Event Log Verification

Review the Windows Update event logs in Event Viewer under Applications and Services Logs > Microsoft > Windows > WindowsUpdateClient.

Security Impact

Installing KB5078738 significantly improves the security posture of Windows Server systems by addressing critical vulnerabilities in Internet Explorer. Organizations should prioritize the deployment of this update to protect against potential exploitation of these vulnerabilities.