KB5002841 — Security Update for SharePoint Server 2016

Overview

KB5002841 is a critical security update released on February 10, 2026, for Microsoft SharePoint Server 2016. This update addresses multiple high-severity vulnerabilities that could allow remote code execution and elevation of privilege attacks against SharePoint Enterprise Server 2016 installations. Organizations running SharePoint Server 2016 should prioritize the deployment of this security update to maintain system security and compliance.

Security Vulnerabilities Addressed

This security update resolves several critical vulnerabilities in SharePoint Server 2016 components:

Remote Code Execution Vulnerability

A critical vulnerability in SharePoint's web application processing engine allows attackers to execute arbitrary code on the SharePoint server. This vulnerability affects how SharePoint processes user-supplied input in web parts and custom applications. Successful exploitation could result in complete system compromise.

Elevation of Privilege Vulnerability

SharePoint's authentication subsystem contains a vulnerability that allows authenticated users to bypass security boundaries and gain unauthorized access to restricted resources. This affects both Windows-integrated authentication and forms-based authentication scenarios.

Memory Corruption Vulnerabilities

Multiple memory corruption issues exist in SharePoint's document processing components. These vulnerabilities could be exploited through specially crafted documents uploaded to SharePoint document libraries, potentially leading to system instability or code execution.

Workflow Processing Security Flaws

SharePoint's workflow processing engine contains input validation flaws that could allow malicious workflows to execute unauthorized operations or access restricted system resources.

Affected Systems

This security update applies specifically to:

Security Fixes Included

Web Application Security Enhancements

The update implements comprehensive input validation improvements across SharePoint's web application framework. Enhanced sanitization routines prevent malicious script injection and code execution attempts through web parts and custom applications. These changes strengthen SharePoint's defense against cross-site scripting (XSS) and remote code execution attacks.

Authentication System Hardening

SharePoint's authentication mechanisms receive significant security improvements with this update. Enhanced permission validation ensures proper enforcement of security boundaries, preventing unauthorized access to restricted SharePoint resources. The fixes apply to all supported authentication methods including Windows authentication, forms-based authentication, and SAML-based authentication.

Document Processing Security

Critical security enhancements in SharePoint's document processing engine prevent memory corruption attacks through malformed documents. Improved bounds checking and memory allocation routines protect against buffer overflow vulnerabilities in document libraries and file upload mechanisms.

Workflow Security Improvements

The workflow processing engine receives enhanced security validation to prevent execution of malicious workflows. Stricter validation of workflow definitions and execution contexts ensures that workflows cannot perform unauthorized operations or access restricted system resources.

Installation Requirements

System Prerequisites

• SharePoint Server 2016 with Service Pack 1 (build 16.0.4351.1000) or later
• Windows Server 2012 R2 or Windows Server 2016
• Microsoft .NET Framework 4.6 or later
• Minimum 500 MB free disk space on system drive
• 8 GB RAM minimum (16 GB recommended for production environments)

Service Requirements

All SharePoint services must be running during update installation. The following services are automatically managed during the update process:

• SharePoint Administration Service
• SharePoint Timer Service
• SharePoint Search Host Controller Service
• SharePoint Server Search Service
• SharePoint User Code Host Service

Deployment Considerations

For SharePoint farms with multiple servers, install the update on all servers in the following order:

1. Database servers (if SharePoint binaries are installed)
2. Application servers
3. Web front-end servers
4. Central Administration server (last)

Run the SharePoint Products Configuration Wizard on each server after installing the update to complete the configuration changes.

Post-Installation Verification

After installing KB5002841, verify successful deployment using the following methods:

PowerShell Verification

Get-SPProduct -Local | Where-Object {$_.ProductName -like "*SharePoint*"}

This command displays installed SharePoint products and their current patch levels. Verify that the build number reflects the updated version.

Central Administration Verification

Navigate to Central Administration > System Settings > Manage servers in this farm. Verify that all servers show the updated build number and that no configuration issues are reported.

Event Log Verification

Check the Windows Application Event Log for SharePoint-related events. Successful installation should not generate error events related to SharePoint services or components.

Rollback Considerations

This security update cannot be uninstalled once applied. Organizations should create comprehensive backups of SharePoint databases and configuration before applying the update. In case of issues, restoration from backup may be necessary.