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CVE-2026-21243— Windows Lightweight Directory Access Protocol (LDAP) Denial of Service Vulnerability

Quick assessment

Affected
Microsoft Windows Server 2019
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Microsoft Lightweight Directory Access Protocol（LDAP）是美国微软（Microsoft）公司的一种目录服务协议，在 TCP/IP 堆栈之上的层上运行。 Microsoft Lightweight Directory Access Protocol（LDAP）存在代码问题漏洞。攻击者利用该漏洞导致系统拒绝服务。以下产品和版本受到影响：Windows Server 2019,Windows Server 2019 (Server Core installati

CVSS 7.5 · High EPSS 1.42% · P72

Possible ATT&CK Techniques 1 AI

T1499 · Endpoint Denial of Service

Affected Version Matrix 6

VendorProduct Version RangeStatus
Microsoft Windows Server 2019 10.0.17763.0< 10.0.17763.8389 affected
Microsoft Windows Server 2019 (Server Core installation) 10.0.17763.0< 10.0.17763.8389 affected
Microsoft Windows Server 2022 10.0.20348.0< 10.0.20348.4773 affected
Microsoft Windows Server 2022, 23H2 Edition (Server Core installation) 10.0.25398.0< 10.0.25398.2149 affected
Microsoft Windows Server 2025 10.0.26100.0< 10.0.26100.32370 affected
Microsoft Windows Server 2025 (Server Core installation) 10.0.26100.0< 10.0.26100.32370 affected
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I. Basic Information for CVE-2026-21243

Vulnerability Information
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Vulnerability Title
Windows Lightweight Directory Access Protocol (LDAP) Denial of Service Vulnerability
Source: CVE Program / CVE List V5
Vulnerability Description
Null pointer dereference in Windows LDAP - Lightweight Directory Access Protocol allows an unauthorized attacker to deny service over a network.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
空指针解引用
Source: CVE Program / CVE List V5
Vulnerability Title
Microsoft Lightweight Directory Access Protocol 代码问题漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Microsoft Lightweight Directory Access Protocol（LDAP）是美国微软（Microsoft）公司的一种目录服务协议，在 TCP/IP 堆栈之上的层上运行。 Microsoft Lightweight Directory Access Protocol（LDAP）存在代码问题漏洞。攻击者利用该漏洞导致系统拒绝服务。以下产品和版本受到影响：Windows Server 2019,Windows Server 2019 (Server Core installati
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Microsoft Windows Server 2019 10.0.17763.0 ~ 10.0.17763.8389 -
Microsoft Windows Server 2019 (Server Core installation) 10.0.17763.0 ~ 10.0.17763.8389 -
Microsoft Windows Server 2022 10.0.20348.0 ~ 10.0.20348.4773 -
Microsoft Windows Server 2022, 23H2 Edition (Server Core installation) 10.0.25398.0 ~ 10.0.25398.2149 -
Microsoft Windows Server 2025 10.0.26100.0 ~ 10.0.26100.32370 -
Microsoft Windows Server 2025 (Server Core installation) 10.0.26100.0 ~ 10.0.26100.32370 -

II. Public POCs for CVE-2026-21243

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III. Intelligence Information for CVE-2026-21243

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Same Patch Batch · Microsoft · 2026-02-10 · 54 CVEs total

CVE-2026-21531 9.8 CRITICAL Azure SDK for Python Remote Code Execution Vulnerability
CVE-2026-21510 8.8 HIGH Windows Shell Security Feature Bypass Vulnerability
CVE-2026-21537 8.8 HIGH Microsoft Defender for Endpoint Linux Extension Remote Code Execution Vulnerability
CVE-2026-21513 8.8 HIGH MSHTML Framework Security Feature Bypass Vulnerability
CVE-2026-21518 8.8 HIGH GitHub Copilot and Visual Studio Code Security Feature Bypass Vulnerability
CVE-2026-21255 8.8 HIGH Windows Hyper-V Security Feature Bypass Vulnerability
CVE-2026-21256 8.8 HIGH GitHub Copilot and Visual Studio Remote Code Execution Vulnerability
CVE-2026-21516 8.8 HIGH GitHub Copilot for Jetbrains Remote Code Execution Vulnerability
CVE-2026-21228 8.1 HIGH Azure Local Remote Code Execution Vulnerability
CVE-2026-21229 8.0 HIGH Power BI Remote Code Execution Vulnerability
CVE-2026-21257 8.0 HIGH GitHub Copilot and Visual Studio Elevation of Privilege Vulnerability
CVE-2026-21523 8.0 HIGH GitHub Copilot and Visual Studio Code Remote Code Execution Vulnerability
CVE-2026-21251 7.8 HIGH Cluster Client Failover (CCF) Elevation of Privilege Vulnerability
CVE-2026-21533 7.8 HIGH Windows Remote Desktop Services Elevation of Privilege Vulnerability
CVE-2026-21514 7.8 HIGH Microsoft Word Security Feature Bypass Vulnerability
CVE-2026-21236 7.8 HIGH Windows Ancillary Function Driver for WinSock Elevation of Privilege Vulnerability
CVE-2026-21238 7.8 HIGH Windows Ancillary Function Driver for WinSock Elevation of Privilege Vulnerability
CVE-2026-21231 7.8 HIGH Windows Kernel Elevation of Privilege Vulnerability
CVE-2026-21232 7.8 HIGH Windows HTTP.sys Elevation of Privilege Vulnerability
CVE-2026-21239 7.8 HIGH Windows Kernel Elevation of Privilege Vulnerability

Showing top 20 of 54 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Windows Server 2019
Same vendor: Microsoft
Same weakness: CWE-476

V. Comments for CVE-2026-21243

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