KB5002834 is a February 10, 2026 security update for SharePoint Server 2019 that addresses critical vulnerabilities including remote code execution and cross-site scripting flaws. This update is essential for maintaining security in enterprise SharePoint environments and requires SharePoint Server 2019 with Service Pack 1 or later.
KB5002834Microsoft SharePoint ServerSharePoint
KB5002834 — Security Update for SharePoint Server 2019
KB5002834 is a February 2026 security update that addresses multiple vulnerabilities in SharePoint Server 2019, including remote code execution and cross-site scripting flaws affecting enterprise SharePoint deployments.
Emanuel DE ALMEIDAKB5002834 is a February 2026 security update that addresses multiple vulnerabilities in SharePoint Server 2019, including remote code execution and cross-site scripting flaws affecting enterprise SharePoint deployments.
Overview
In This Article
- Issue Description
- Root Cause
- 1Fixes remote code execution vulnerability in SharePoint web parts
- 2Resolves cross-site scripting vulnerabilities in SharePoint pages
- 3Patches information disclosure vulnerability in SharePoint services
- 4Fixes elevation of privilege vulnerability in SharePoint Central Administration
- Installation
- Known Issues
- Frequently Asked Questions
Applies to
SharePoint Server 2019
Issue Description
Issue Description
This security update addresses several vulnerabilities in SharePoint Server 2019 that could allow attackers to exploit the following security flaws:
- Remote Code Execution: Attackers could execute arbitrary code on the SharePoint server through specially crafted requests
- Cross-Site Scripting (XSS): Malicious scripts could be injected into SharePoint pages, potentially compromising user sessions
- Information Disclosure: Sensitive information could be exposed through improper access controls in certain SharePoint components
- Elevation of Privilege: Users could gain unauthorized access to restricted SharePoint resources
These vulnerabilities affect SharePoint Server 2019 installations across all deployment scenarios, including on-premises farms and hybrid configurations.
Root Cause
Root Cause
The vulnerabilities stem from insufficient input validation in SharePoint Server 2019 components, improper handling of user-supplied data in web parts, and inadequate access control mechanisms in certain SharePoint services. These issues allow malicious actors to bypass security boundaries and execute unauthorized operations within the SharePoint environment.
1
Fixes remote code execution vulnerability in SharePoint web parts
This update patches a critical remote code execution vulnerability in SharePoint Server 2019 web parts. The fix implements enhanced input validation and sanitization mechanisms to prevent malicious code injection through specially crafted web part parameters. The update modifies the following components:
- SharePoint web part rendering engine
- Input validation libraries
- Request processing pipeline
This fix prevents attackers from exploiting web part vulnerabilities to execute arbitrary code on the SharePoint server with elevated privileges.
2
Resolves cross-site scripting vulnerabilities in SharePoint pages
The update addresses multiple cross-site scripting (XSS) vulnerabilities in SharePoint Server 2019 by implementing improved output encoding and content sanitization. The fixes apply to:
- SharePoint list and library views
- Search result pages
- User profile pages
- Custom application pages
These changes prevent malicious scripts from being executed in users' browsers when viewing SharePoint content, protecting against session hijacking and data theft.
3
Patches information disclosure vulnerability in SharePoint services
This security fix addresses an information disclosure vulnerability that could allow unauthorized users to access sensitive SharePoint data. The update strengthens access control mechanisms in:
- SharePoint REST API endpoints
- Search service components
- User profile service
- Business Connectivity Services
The fix ensures that proper authorization checks are performed before returning sensitive information, preventing unauthorized data exposure.
4
Fixes elevation of privilege vulnerability in SharePoint Central Administration
The update resolves an elevation of privilege vulnerability in SharePoint Central Administration that could allow users to gain unauthorized administrative access. The fix implements:
- Enhanced permission validation in Central Administration pages
- Improved role-based access control mechanisms
- Strengthened authentication checks for administrative operations
This prevents users from bypassing security boundaries to perform unauthorized administrative tasks.
Installation
Installation
KB5002834 can be installed through multiple deployment methods:
Microsoft Update Catalog
Download the update package directly from Microsoft Update Catalog for manual installation. The update file size is approximately 85 MB and requires a system restart after installation.
Windows Server Update Services (WSUS)
Enterprise environments can deploy this update through WSUS by approving KB5002834 for SharePoint Server 2019 systems. The update will be automatically distributed to managed SharePoint servers.
System Center Configuration Manager (SCCM)
Deploy the update through SCCM software update management by creating a deployment package for KB5002834 and targeting SharePoint Server 2019 systems.
Prerequisites
- SharePoint Server 2019 with Service Pack 1 or later
- Minimum 500 MB free disk space on system drive
- Administrative privileges on SharePoint server
- All SharePoint services must be running before installation
Installation Time: Approximately 15-30 minutes depending on server configuration. A system restart is required to complete the installation.
Known Issues
Known Issues
The following issues have been reported after installing KB5002834:
SharePoint Timer Service Restart Required
After installation, the SharePoint Timer Service may require manual restart on some systems. If SharePoint workflows or scheduled tasks are not functioning properly, restart the SharePoint Timer Service using the following PowerShell command:
Restart-Service SPTimerV4Search Service Indexing Delays
Some environments may experience temporary delays in search indexing for 2-4 hours after update installation. This is expected behavior as the search service reinitializes security components. No action is required as indexing will resume automatically.
Custom Web Parts Compatibility
Third-party or custom web parts that rely on deprecated APIs may experience compatibility issues. Test custom web parts thoroughly in a development environment before deploying to production. Contact your web part vendor for updated versions if issues occur.
Important: Always test this update in a non-production environment before deploying to production SharePoint farms.
Overview
KB5002834 is a critical security update released on February 10, 2026, for SharePoint Server 2019. This update addresses multiple high-severity vulnerabilities that could allow attackers to execute remote code, perform cross-site scripting attacks, disclose sensitive information, and elevate privileges within SharePoint environments.
Security Vulnerabilities Addressed
This security update resolves several critical vulnerabilities in SharePoint Server 2019:
Remote Code Execution Vulnerability
A critical vulnerability in SharePoint web parts could allow authenticated attackers to execute arbitrary code on the SharePoint server. This vulnerability affects the web part rendering engine and could be exploited through specially crafted web part parameters. Successful exploitation could result in complete server compromise.
Cross-Site Scripting Vulnerabilities
Multiple XSS vulnerabilities in SharePoint pages could allow attackers to inject malicious scripts that execute in users' browsers. These vulnerabilities affect list views, search results, and user profile pages. Exploitation could lead to session hijacking, credential theft, and unauthorized actions performed on behalf of legitimate users.
Information Disclosure Vulnerability
An information disclosure vulnerability in SharePoint services could allow unauthorized users to access sensitive data through improper access controls. This affects REST API endpoints, search services, and user profile information, potentially exposing confidential business data.
Elevation of Privilege Vulnerability
A privilege escalation vulnerability in SharePoint Central Administration could allow users to gain unauthorized administrative access. This vulnerability affects permission validation mechanisms and could be exploited to perform unauthorized administrative operations.
Affected Systems
| Product | Version | Status |
|---|---|---|
| SharePoint Server 2019 | All versions | Affected |
| SharePoint Server 2016 | All versions | Not affected |
| SharePoint Server 2013 | All versions | Not affected |
Installation Requirements
Before installing KB5002834, ensure the following prerequisites are met:
- SharePoint Version: SharePoint Server 2019 with Service Pack 1 or later
- Disk Space: Minimum 500 MB free space on system drive
- Permissions: Local administrator rights on SharePoint server
- Services: All SharePoint services must be running
- Backup: Complete farm backup recommended before installation
Deployment Methods
Microsoft Update Catalog
For manual installation, download the update package from Microsoft Update Catalog. The package includes all necessary files and can be installed using the standard Windows Update installer. File size is approximately 85 MB.
Enterprise Deployment
Enterprise environments should use WSUS or SCCM for centralized deployment. The update can be approved for automatic installation during maintenance windows. Test deployment in development environments first.
PowerShell Installation Verification
Verify successful installation using PowerShell:
Get-HotFix -Id KB5002834
Get-SPProduct -LocalPost-Installation Considerations
After installing KB5002834, perform the following verification steps:
- Verify all SharePoint services are running properly
- Test critical SharePoint functionality including search and workflows
- Monitor SharePoint logs for any error messages
- Validate custom web parts and third-party solutions
- Confirm user access and permissions are functioning correctly
Note: This update requires a system restart to complete installation. Plan the installation during scheduled maintenance windows to minimize user impact.
Security Impact
Installing KB5002834 significantly improves SharePoint Server 2019 security posture by:
- Preventing remote code execution attacks through web part vulnerabilities
- Blocking cross-site scripting attacks on SharePoint pages
- Protecting sensitive information from unauthorized disclosure
- Preventing privilege escalation in Central Administration
Organizations should prioritize installation of this update due to the critical nature of the vulnerabilities addressed.
Frequently Asked Questions
What does KB5002834 resolve?
KB5002834 resolves multiple critical security vulnerabilities in SharePoint Server 2019, including remote code execution, cross-site scripting, information disclosure, and elevation of privilege vulnerabilities that could compromise SharePoint server security.
Which systems require KB5002834?
KB5002834 is required for all SharePoint Server 2019 installations, regardless of deployment configuration. The update applies to on-premises SharePoint farms and hybrid environments running SharePoint Server 2019.
Is KB5002834 a security update?
Yes, KB5002834 is a critical security update that addresses multiple high-severity vulnerabilities in SharePoint Server 2019. Installation is strongly recommended to protect against potential security exploits.
What are the prerequisites for KB5002834?
Prerequisites include SharePoint Server 2019 with Service Pack 1 or later, minimum 500 MB free disk space, administrative privileges, and all SharePoint services running. A complete farm backup is recommended before installation.
Are there known issues with KB5002834?
Known issues include potential SharePoint Timer Service restart requirements, temporary search indexing delays for 2-4 hours, and possible compatibility issues with custom web parts using deprecated APIs. Testing in non-production environments is recommended.
References (3)
1
Mises à jour de sécurité de SharePoint Server 2019Page officielle de Microsoft pour les mises à jour de sécurité et correctifs de SharePoint Server 2019https://support.microsoft.com/sharepoint-server-2019-updates
2Centre de réponse de sécurité MicrosoftCentre de réponse de sécurité Microsoft pour les avis de sécurité et les informations sur les vulnérabilitéshttps://msrc.microsoft.com
3Centre de mise à jour de SharePoint ServerGuide complet sur les mises à jour et la maintenance de SharePoint Serverhttps://learn.microsoft.com/sharepoint/upgrade-and-update/sharepoint-updates
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