Overview
On February 11, 2026, NSFOCUS CERT monitored Microsoft’s release of its February security update patches, addressing 59 security issues across widely used products such as Windows, Azure, Microsoft Office, and Visual Studio Code. These vulnerabilities include privilege escalation, remote code execution, and other high-risk vulnerabilities.
In this monthly update, 5 vulnerabilities are rated as Critical in severity, 52 are rated as Important, and 2 are rated as Moderate.
Six of these vulnerabilities have been detected as being exploited in the wild:
- Windows Shell Security Feature Bypass Vulnerability (CVE-2026-21510)
- MSHTML Framework Security Feature Bypass Vulnerability (CVE-2026-21513)
- Microsoft Word Security Feature Bypass Vulnerability (CVE-2026-21514)
- Desktop Window Manager Privilege Escalation Vulnerability (CVE-2026-21519)
- Windows Remote Access Connection Manager Denial of Service Vulnerability (CVE-2026-21525)
- Windows Remote Desktop Service Privilege Escalation Vulnerability (CVE-2026-21533)
Reference Link:
https://msrc.microsoft.com/update-guide/releaseNote/2026-Feb
Key Vulnerabilities
The following vulnerabilities are highlighted based on product popularity and severity. Users are strongly advised to prioritize these:
Windows Storage Elevation of Privilege Vulnerability (CVE-2026-21508):
A privilege escalation vulnerability exists in Windows Storage (windows.storage.dll) due to a logical flaw in an undisclosed function. An attacker could manipulate the current user’s registry entries, hijacking the CLSID parameter of CoCreateInstance when called by a high-privilege process, thereby achieving privilege escalation. The CVSS score is 7.0.
Reference Link:
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21508
Windows Shell Security Feature Bypass Vulnerability (CVE-2026-21510):
A security feature bypass vulnerability exists in Windows Shell due to a failure in its protection mechanisms. An attacker could exploit this by tricking users into clicking malicious links or shortcut files, bypassing Windows SmartScreen and Windows Shell security prompts. This allows attacker-controlled content to execute without user warnings or consent. This vulnerability has been observed in active exploits. The CVSS score is 8.8.
Reference Link:
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21510
MSHTML Framework Security Feature Bypass Vulnerability (CVE-2026-21513):
A security feature bypass vulnerability exists in the MSHTML framework due to a failure in its protection mechanisms. Attackers could exploit this by inducing users to open malicious HTML files or shortcut (.lnk) files via links, email attachments, or downloads. The crafted file manipulates the browser and Windows Shell handling mechanisms, causing its content to be executed directly by the operating system. This vulnerability has been observed in active exploits. The CVSS score is 8.8.
Reference Link:
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21513
Windows Remote Access Connection Manager Denial of Service Vulnerability (CVE-2026-21525):
A denial of service vulnerability exists in the Windows Remote Access Connection Manager due to a null pointer reference. An unauthenticated attacker could exploit this to cause a local denial of service. This vulnerability has been observed in active exploits. The CVSS score is 6.2.
Reference Link:
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21525
Microsoft Word Security Feature Bypass Vulnerability (CVE-2026-21514):
A security feature bypass vulnerability exists in Microsoft Word due to reliance on untrusted input in Microsoft Office Word’s security decisions. An unauthenticated attacker could bypass local security features. This vulnerability has been observed in active exploits. The CVSS score is 7.8.
Reference Link:
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21514
Desktop Window Manager Elevation of Privilege Vulnerability (CVE-2026-21519):
An elevation of privilege vulnerability exists in the Desktop Window Manager due to accessing resources with an incompatible type. An authenticated attacker could exploit this to elevate privileges locally. This vulnerability has been observed in active exploits. The CVSS score is 7.8.
Reference Link:
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21519
Windows Remote Desktop Services Elevation of Privilege Vulnerability (CVE-2026-21533):
An elevation of privilege vulnerability exists in Windows Remote Desktop Services due to improper permission management. An authenticated attacker could exploit this to elevate privileges locally. This vulnerability has been observed in active exploits. The CVSS score is 7.8.
Reference Link:
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21533
Windows Notepad Remote Code Execution Vulnerability (CVE-2026-20841):
A remote code execution vulnerability exists in Windows Notepad. Due to improper neutralization of user input, an attacker could exploit this by tricking a user into clicking a malicious link in a Markdown file opened in Notepad, causing the application to launch an unvalidated protocol and load and execute a remote file. The CVSS score is 8.8.
Reference Link:
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20841
Azure Local Remote Code Execution Vulnerability (CVE-2026-21228):
A local remote code execution vulnerability exists in Azure due to improper certificate validation in Azure Local. This allows unauthorized attackers to execute code over the network. The CVSS score is 8.1.
Reference Link:
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21228
Scope of Impact
The following are the affected product versions of some key vulnerabilities. For the scope of products affected by other vulnerabilities, please refer to the official announcement link.
The following are the affected product versions of some key vulnerabilities. For the scope of products affected by other vulnerabilities, please refer to the official announcement link.
| Vulnerability Number | Affected product versions |
|---|---|
| CVE-2026-21508 CVE-2026-21510 CVE-2026-21513 CVE-2026-21525 | Windows 11 version 26H1 for x64-based Systems Windows 11 Version 26H1 for ARM64-based Systems Windows Server 2012 R2 (Server Core installation) Windows Server 2012 R2 Windows Server 2012 (Server Core installation) Windows Server 2012 Windows Server 2016 (Server Core installation) Windows Server 2016 Windows 10 Version 1607 for x64-based Systems Windows 10 Version 1607 for 32-bit Systems Windows Server 2025 Windows 11 Version 24H2 for x64-based Systems Windows 11 Version 24H2 for ARM64-based Systems Windows Server 2022, 23H2 Edition (Server Core installation) Windows 11 Version 23H2 for x64-based Systems Windows 11 Version 23H2 for ARM64-based Systems Windows 11 Version 25H2 for x64-based Systems Windows 11 Version 25H2 for ARM64-based Systems Windows Server 2025 (Server Core installation) Windows 10 Version 22H2 for 32-bit Systems Windows 10 Version 22H2 for ARM64-based Systems Windows 10 Version 22H2 for x64-based Systems Windows 10 Version 21H2 for x64-based Systems Windows 10 Version 21H2 for ARM64-based Systems Windows 10 Version 21H2 for 32-bit Systems Windows Server 2022 (Server Core installation) Windows Server 2022 Windows Server 2019 (Server Core installation) Windows Server 2019 Windows 10 Version 1809 for x64-based Systems Windows 10 Version 1809 for 32-bit Systems |
| CVE-2026-21514 | Microsoft Office LTSC for Mac 2024 Microsoft Office LTSC 2024 for 64-bit editions Microsoft Office LTSC 2024 for 32-bit editions Microsoft Office LTSC 2021 for 32-bit editions Microsoft Office LTSC 2021 for 64-bit editions Microsoft Office LTSC for Mac 2021 Microsoft 365 Apps for Enterprise for 64-bit Systems Microsoft 365 Apps for Enterprise for 32-bit Systems |
| CVE-2026-21519CVE-2026-21533 | Windows 11 version 26H1 for x64-based Systems Windows 11 Version 26H1 for ARM64-based Systems Windows Server 2016 (Server Core installation) Windows Server 2016Windows 10 Version 1607 for x64-based Systems Windows 10 Version 1607 for 32-bit Systems Windows Server 2025 Windows 11 Version 24H2 for x64-based Systems Windows 11 Version 24H2 for ARM64-based Systems Windows Server 2022, 23H2 Edition (Server Core installation) Windows 11 Version 23H2 for x64-based Systems Windows 11 Version 23H2 for ARM64-based Systems Windows 11 Version 25H2 for x64-based Systems Windows 11 Version 25H2 for ARM64-based Systems Windows Server 2025 (Server Core installation) Windows 10 Version 22H2 for 32-bit Systems Windows 10 Version 22H2 for ARM64-based Systems Windows 10 Version 22H2 for x64-based Systems Windows 10 Version 21H2 for x64-based Systems Windows 10 Version 21H2 for ARM64-based Systems Windows 10 Version 21H2 for 32-bit SystemsWindows Server 2022 (Server Core installation) Windows Server 2022 Windows Server 2019 (Server Core installation) Windows Server 2019Windows 10 Version 1809 for x64-based Systems Windows 10 Version 1809 for 32-bit Systems |
| CVE-2026-20841 | Windows Notepad |
| CVE-2026-21228 | Azure Local |
Mitigation
Patch update
At present, Microsoft has officially released security patches to fix the above vulnerabilities for supported product versions. It is strongly recommended that affected users install patches as soon as possible for protection. The official download link:
https://msrc.microsoft.com/update-guide/releaseNote/2026-Feb
Note: Patch updates for Windows Update may fail due to network problems, computer environment problems, etc. After installing the patch, users should check whether the patch has been successfully updated in time.
Right-click the Windows icon, select “Settings (N)”, select “Update and Security”-“Windows Update”, view the prompt information on this page, or click “View Update History” to view the historical update status.
For updates that have not been successfully installed, you can click the update name to jump to the Microsoft official download page. It is recommended that users click the link on this page and go to the “Microsoft Update Catalog” website to download the independent program package and install it.
Appendix: Vulnerability List
| Affected products | CVE No. | Vulnerability Title | Severity |
|---|---|---|---|
| Azure | CVE-2026-21522 | Microsoft ACI Confidential Containers – Privilege Escalation Vulnerability | Critical |
| Azure | CVE-2026-21532 | Azure Function – Information Disclosure Vulnerability | Critical |
| Azure | CVE-2026-23655 | Microsoft ACI Confidential Containers – Information Disclosure Vulnerability | Critical |
| Azure | CVE-2026-24300 | Azure Front Door – Privilege Escalation Vulnerability | Critical |
| Azure | CVE-2026-24302 | Azure Arc – Privilege Escalation Vulnerability | Critical |
| Apps | CVE-2026-20841 | Windows Notepad App – Remote Code Execution Vulnerability | Important |
| Windows | CVE-2026-20846 | GDI+ – Denial of Service Vulnerability | Important |
| .NET 8.0 installed on Mac OS,.NET 9.0 installed on Windows,.NET 8.0 installed on Linux,.NET 9.0 installed on Linux,.NET 10.0 installed on Mac OS,.NET 10.0 installed on Linux,.NET 9.0 installed on Mac OS,.NET 8.0 installed on Windows,.NET 10.0 installed on Windows | CVE-2026-21218 | .NET – Denial of Service Vulnerability | Important |
| Windows | CVE-2026-21222 | Windows Kernel – Information Disclosure Vulnerability | Important |
| Azure | CVE-2026-21228 | Azure Local – Remote Code Execution Vulnerability | Important |
| Power BI Report Server | CVE-2026-21229 | Power BI– Remote Code Execution Vulnerability | Important |
| Windows | CVE-2026-21231 | Windows Kernel– Privilege Escalation Vulnerability | Important |
| Windows | CVE-2026-21232 | Windows HTTP.sys – Privilege Escalation Vulnerability | Important |
| Windows | CVE-2026-21234 | Windows Connected Devices Platform Service – Privilege Escalation Vulnerability | Important |
| Windows | CVE-2026-21235 | Windows Graphics Component – Privilege Escalation Vulnerability | Important |
| Windows | CVE-2026-21236 | Windows Ancillary Function Driver for WinSock – Privilege Escalation Vulnerability | Important |
| Windows | CVE-2026-21237 | Windows Subsystem for Linux – Privilege Escalation Vulnerability | Important |
| Windows | CVE-2026-21238 | Windows Ancillary Function Driver for WinSoc – Privilege Escalation Vulnerability | Important |
| Windows | CVE-2026-21239 | Windows Kernel – Privilege Escalation Vulnerability | Important |
| Windows | CVE-2026-21240 | Windows HTTP.sys – Privilege Escalation Vulnerability | Important |
| Windows | CVE-2026-21241 | Windows Ancillary Function Driver for WinSock – Privilege Escalation Vulnerability | Important |
| Windows | CVE-2026-21242 | Windows Subsystem for Linux – Privilege Escalation Vulnerability | Important |
| Windows | CVE-2026-21243 | Windows Lightweight Directory Access Protocol (LDAP)– Denial of Service Vulnerability | Important |
| Windows | CVE-2026-21244 | Windows Hyper-V – Remote Code Execution Vulnerability | Important |
| Windows | CVE-2026-21245 | Windows Kernel – Privilege Escalation Vulnerability | Important |
| Windows | CVE-2026-21246 | Windows Graphics Component – Privilege Escalation Vulnerability | Important |
| Windows | CVE-2026-21247 | Windows Hyper-V – Remote Code Execution Vulnerability | Important |
| Windows | CVE-2026-21248 | Windows Hyper-V – Remote Code Execution Vulnerability | Important |
| Windows | CVE-2026-21249 | Windows NTLM – Spoofing Vulnerability | Important |
| Windows | CVE-2026-21250 | Windows HTTP.sys – Privilege Escalation Vulnerability | Important |
| Windows | CVE-2026-21251 | Cluster Client Failover (CCF) – Privilege Escalation Vulnerability | Important |
| Windows | CVE-2026-21253 | Mailslot File System – Privilege Escalation Vulnerability | Important |
| Windows | CVE-2026-21255 | Windows Hyper-V – Security Feature Bypass Vulnerability | Important |
| Microsoft Visual Studio | CVE-2026-21256 | GitHub Copilot and Visual Studio – Remote Code Execution Vulnerability | Important |
| Microsoft Visual Studio | CVE-2026-21257 | GitHub Copilot and Visual Studio – Privilege Escalation Vulnerability | Important |
| Microsoft Office | CVE-2026-21258 | Microsoft Excel – Information Disclosure Vulnerability | Important |
| Microsoft Office | CVE-2026-21259 | Microsoft Excel – Privilege Escalation Vulnerability | Important |
| Microsoft Office | CVE-2026-21260 | Microsoft Outlook – Spoofing Vulnerability | Important |
| Microsoft Office | CVE-2026-21261 | Microsoft Excel – Information Disclosure Vulnerability | Important |
| Windows | CVE-2026-21508 | Windows Storage – Privilege Escalation Vulnerability | Important |
| Windows | CVE-2026-21510 | Windows Shell – Security Feature Bypass Vulnerability | Important |
| Microsoft Office | CVE-2026-21511 | Microsoft Outlook – Spoofing Vulnerability | Important |
| Azure | CVE-2026-21512 | Azure DevOps Server – Denial of Service Vulnerability (Scripting Engine) | Important |
| Windows | CVE-2026-21513 | MSHTML Framework – Security Feature Bypass Vulnerability | Important |
| Microsoft Office | CVE-2026-21514 | Microsoft Word – Security Feature Bypass Vulnerability | Important |
| Windows | CVE-2026-21517 | Windows App for Mac Installer – Privilege Escalation Vulnerability | Important |
| Visual Studio Code | CVE-2026-21518 | GitHub Copilot and Visual Studio Code – Security Feature Bypass Vulnerability | Important |
| Windows | CVE-2026-21519 | Desktop Window Manager – Privilege Escalation Vulnerability | Important |
| Visual Studio Code | CVE-2026-21523 | GitHub Copilot and Visual Studio Code – Remote Code Execution Vulnerability | Important |
| Microsoft Exchange Server Subscription Edition RTM,Microsoft Exchange Server | CVE-2026-21527 | Microsoft Exchange Server – Spoofing Vulnerability | Important |
| Azure | CVE-2026-21528 | Azure IoT Explorer – Information Disclosure Vulnerability | Important |
| Azure | CVE-2026-21529 | Azure HDInsight – Spoofing Vulnerability | Important |
| Azure | CVE-2026-21531 | Azure SDK for Python – Remote Code Execution Vulnerability | Important |
| Windows | CVE-2026-21533 | Windows Remote Desktop Services – Privilege Escalation Vulnerability | Important |
| System Center | CVE-2026-21537 | Microsoft Defender for Endpoint Linux Extension – Remote Code Execution Vulnerability | Important |
| Microsoft Edge (Chromium-based) | CVE-2026-0391 | Microsoft Edge (Chromium-based) for Android – Spoofing Vulnerability | Moderate |
| Windows | CVE-2026-21525 | Windows Remote Access Connection Manager – Denial of Service Vulnerability | Moderate |
Statement
This advisory is only used to describe a potential risk. NSFOCUS does not provide any commitment or promise on this advisory. NSFOCUS and the author will not bear any liability for any direct and/or indirect consequences and losses caused by transmitting and/or using this advisory.
NSFOCUS reserves all the rights to modify and interpret this advisory. Please include this statement paragraph when reproducing or transferring this advisory. Do not modify this advisory, add/delete any information to/from it, or use this advisory for commercial purposes without permission from NSFOCUS.
About NSFOCUS
NSFOCUS, a pioneering leader in cybersecurity, is dedicated to safeguarding telecommunications, Internet service providers, hosting providers, and enterprises from sophisticated cyberattacks.
Founded in 2000, NSFOCUS operates globally with over 4000 employees at two headquarters in Beijing, China, and Santa Clara, CA, USA, and over 50 offices worldwide. It has a proven track record of protecting over 25% of the Fortune Global 500 companies, including four of the five largest banks and six of the world’s top ten telecommunications companies.
Leveraging technical prowess and innovation, NSFOCUS delivers a comprehensive suite of security solutions, including the Intelligent Security Operations Platform (ISOP) for modern SOC, DDoS Protection, Continuous Threat Exposure Management (CTEM) Service and Web Application and API Protection (WAAP). All the solutions and services are augmented by the Security Large Language Model (SecLLM), ML, patented algorithms and other cutting-edge research achievements developed by NSFOCUS.
