Microsoft Server Windows Server Vulnerabilities & Security Advisories
1523 advisories tracked · Microsoft Security Update Guide (MSRC) · 61 listed in the CISA Known Exploited Vulnerabilities catalog
Every row below is a published Microsoft Server advisory that VulniPulse classified as Windows Server, with the CVEs, affected and fixed releases and exploitation status the vendor stated. Severity mix: 65 critical, 1087 high, 417 medium, 4 low.
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Source
Microsoft Security Update Guide (MSRC)
Polled via the official MSRC Security Update Guide RSS feed (api.msrc.microsoft.com, no credentials required), scoped to SERVER products only — Windows Server, Exchange, SQL Server, SharePoint, Hyper-V and companion server roles. Client-only CVEs (Edge, Office apps, consumer Windows) are filtered out via the monthly CVRF document's affected-product list.
Latest MS Server Windows Server advisories
High [CVE-2026-25184] Applocker Filter Driver (applockerfltr.sys) Elevation of Privilege Vulnerability
Concurrent execution using shared resource with improper synchronization ('race condition') in Applocker Filter Driver (applockerfltr.sys) allows an authorized attacker to elevate privileges locally. Affected products named by the advisory: Windows Server 2022, 23H2 Edition (Server Core installation); Windows Server 2025; Windows Server 2025 (Server Core installation).
High [CVE-2026-20930] Windows Management Services Elevation of Privilege Vulnerability
Concurrent execution using shared resource with improper synchronization ('race condition') in Windows Management Services allows an authorized attacker to elevate privileges locally. Affected products named by the advisory: Windows Server 2019; Windows Server 2019 (Server Core installation); Windows Server 2022; Windows Server 2022, 23H2 Edition (Server Core installation); and 2 more. Affected products named by the advisory: Windows Server 2025 (Server Core installation).
High [CVE-2026-20846] GDI+ Denial of Service Vulnerability
Buffer over-read in Windows GDI+ allows an unauthorized attacker to deny service over a network. Affected products named by the advisory: Windows Server 2012; Windows Server 2012 (Server Core installation); Windows Server 2012 R2; Windows Server 2012 R2 (Server Core installation); and 8 more. Affected products named by the advisory: Windows Server 2016 (Server Core installation); Windows Server 2019 (Server Core installation); Windows Server 2022, 23H2 Edition (Server Core installation); Windows Server 2025 (Server Core installation).
High [CVE-2026-21231] Windows Kernel Elevation of Privilege Vulnerability
Concurrent execution using shared resource with improper synchronization ('race condition') in Windows Kernel allows an authorized attacker to elevate privileges locally. Affected products named by the advisory: Windows Server 2012; Windows Server 2012 (Server Core installation); Windows Server 2012 R2; Windows Server 2012 R2 (Server Core installation); and 8 more. Affected products named by the advisory: Windows Server 2016 (Server Core installation); Windows Server 2019 (Server Core installation); Windows Server 2022, 23H2 Edition (Server Core installation); Windows Server 2025 (Server Core installation).
High [CVE-2026-21232] Windows HTTP.sys Elevation of Privilege Vulnerability
Untrusted pointer dereference in Windows HTTP.sys allows an authorized attacker to elevate privileges locally. Affected products named by the advisory: Windows Server 2022, 23H2 Edition (Server Core installation); Windows Server 2025; Windows Server 2025 (Server Core installation).
High [CVE-2026-21237] Windows Subsystem for Linux Elevation of Privilege Vulnerability
Concurrent execution using shared resource with improper synchronization ('race condition') in Windows Subsystem for Linux allows an authorized attacker to elevate privileges locally. Affected products named by the advisory: Windows Server 2022; Windows Server 2022, 23H2 Edition (Server Core installation); Windows Server 2025; Windows Server 2025 (Server Core installation).
High [CVE-2026-21238] Windows Ancillary Function Driver for WinSock Elevation of Privilege Vulnerability
Improper access control in Windows Ancillary Function Driver for WinSock allows an authorized attacker to elevate privileges locally. Affected products named by the advisory: Windows Server 2012; Windows Server 2012 (Server Core installation); Windows Server 2012 R2; Windows Server 2012 R2 (Server Core installation); and 8 more. Affected products named by the advisory: Windows Server 2016 (Server Core installation); Windows Server 2019 (Server Core installation); Windows Server 2022, 23H2 Edition (Server Core installation); Windows Server 2025 (Server Core installation).
High [CVE-2026-21241] Windows Ancillary Function Driver for WinSock Elevation of Privilege Vulnerability
Use after free in Windows Ancillary Function Driver for WinSock allows an authorized attacker to elevate privileges locally. Affected products named by the advisory: Windows Server 2022; Windows Server 2022, 23H2 Edition (Server Core installation); Windows Server 2025; Windows Server 2025 (Server Core installation).
High [CVE-2026-21240] Windows HTTP.sys Elevation of Privilege Vulnerability
Time-of-check time-of-use (toctou) race condition in Windows HTTP.sys allows an authorized attacker to elevate privileges locally. Affected products named by the advisory: Windows Server 2019; Windows Server 2019 (Server Core installation); Windows Server 2022; Windows Server 2022, 23H2 Edition (Server Core installation); and 2 more. Affected products named by the advisory: Windows Server 2025 (Server Core installation).
High [CVE-2026-21243] Windows Lightweight Directory Access Protocol (LDAP) Denial of Service Vulnerability
Null pointer dereference in Windows LDAP - Lightweight Directory Access Protocol allows an unauthorized attacker to deny service over a network. Affected products named by the advisory: Windows Server 2019; Windows Server 2019 (Server Core installation); Windows Server 2022; Windows Server 2022, 23H2 Edition (Server Core installation); and 2 more. Affected products named by the advisory: Windows Server 2025 (Server Core installation).
High [CVE-2026-21244] Windows Hyper-V Remote Code Execution Vulnerability
Heap-based buffer overflow in Windows Hyper-V allows an authorized attacker to execute code locally. Affected products named by the advisory: Windows Server 2016; Windows Server 2016 (Server Core installation); Windows Server 2019; Windows Server 2019 (Server Core installation); and 4 more. Affected products named by the advisory: Windows Server 2022, 23H2 Edition (Server Core installation); Windows Server 2025 (Server Core installation).
High [CVE-2026-21251] Cluster Client Failover (CCF) Elevation of Privilege Vulnerability
Use after free in Windows Cluster Client Failover allows an authorized attacker to elevate privileges locally. Affected products named by the advisory: Windows Server 2016; Windows Server 2016 (Server Core installation); Windows Server 2019; Windows Server 2019 (Server Core installation); and 4 more. Affected products named by the advisory: Windows Server 2022, 23H2 Edition (Server Core installation); Windows Server 2025 (Server Core installation).
High [CVE-2026-21253] Mailslot File System Elevation of Privilege Vulnerability
Use after free in Mailslot File System allows an authorized attacker to elevate privileges locally. Affected products named by the advisory: Windows Server 2012; Windows Server 2012 (Server Core installation); Windows Server 2012 R2; Windows Server 2012 R2 (Server Core installation); and 8 more. Affected products named by the advisory: Windows Server 2016 (Server Core installation); Windows Server 2019 (Server Core installation); Windows Server 2022, 23H2 Edition (Server Core installation); Windows Server 2025 (Server Core installation).
High [CVE-2026-21255] Windows Hyper-V Security Feature Bypass Vulnerability
Improper access control in Windows Hyper-V allows an authorized attacker to bypass a security feature locally. Affected products named by the advisory: Windows Server 2016; Windows Server 2016 (Server Core installation); Windows Server 2019; Windows Server 2019 (Server Core installation); and 4 more. Affected products named by the advisory: Windows Server 2022, 23H2 Edition (Server Core installation); Windows Server 2025 (Server Core installation).
High [CVE-2026-21508] Windows Storage Elevation of Privilege Vulnerability
Improper authentication in Windows Storage allows an authorized attacker to elevate privileges locally. Affected products named by the advisory: Windows Server 2012; Windows Server 2012 (Server Core installation); Windows Server 2012 R2; Windows Server 2012 R2 (Server Core installation); and 8 more. Affected products named by the advisory: Windows Server 2016 (Server Core installation); Windows Server 2019 (Server Core installation); Windows Server 2022, 23H2 Edition (Server Core installation); Windows Server 2025 (Server Core installation).
High [CVE-2026-21513] MSHTML Framework Security Feature Bypass Vulnerability
Protection mechanism failure in MSHTML Framework allows an unauthorized attacker to bypass a security feature over a network. Affected products named by the advisory: Windows Server 2012; Windows Server 2012 (Server Core installation); Windows Server 2012 R2; Windows Server 2012 R2 (Server Core installation); and 8 more. Affected products named by the advisory: Windows Server 2016 (Server Core installation); Windows Server 2019 (Server Core installation); Windows Server 2022, 23H2 Edition (Server Core installation); Windows Server 2025 (Server Core installation).
High [CVE-2026-21533] Windows Remote Desktop Services Elevation of Privilege Vulnerability
Improper privilege management in Windows Remote Desktop allows an authorized attacker to elevate privileges locally. Affected products named by the advisory: Windows Server 2012; Windows Server 2012 (Server Core installation); Windows Server 2012 R2; Windows Server 2012 R2 (Server Core installation); and 8 more. Affected products named by the advisory: Windows Server 2016 (Server Core installation); Windows Server 2019 (Server Core installation); Windows Server 2022, 23H2 Edition (Server Core installation); Windows Server 2025 (Server Core installation).
High [CVE-2026-21236] Windows Ancillary Function Driver for WinSock Elevation of Privilege Vulnerability
Heap-based buffer overflow in Windows Ancillary Function Driver for WinSock allows an authorized attacker to elevate privileges locally. Affected products named by the advisory: Windows Server 2012; Windows Server 2012 (Server Core installation); Windows Server 2012 R2; Windows Server 2012 R2 (Server Core installation); and 8 more. Affected products named by the advisory: Windows Server 2016 (Server Core installation); Windows Server 2019 (Server Core installation); Windows Server 2022, 23H2 Edition (Server Core installation); Windows Server 2025 (Server Core installation).
High [CVE-2026-21234] Windows Connected Devices Platform Service Elevation of Privilege Vulnerability
Concurrent execution using shared resource with improper synchronization ('race condition') in Windows Connected Devices Platform Service allows an authorized attacker to elevate privileges locally. Affected products named by the advisory: Windows Server 2019; Windows Server 2019 (Server Core installation); Windows Server 2022; Windows Server 2022, 23H2 Edition (Server Core installation); and 2 more. Affected products named by the advisory: Windows Server 2025 (Server Core installation).
High [CVE-2026-21235] Windows Graphics Component Elevation of Privilege Vulnerability
Use after free in Microsoft Graphics Component allows an authorized attacker to elevate privileges locally. Affected products named by the advisory: Windows Server 2012; Windows Server 2012 (Server Core installation); Windows Server 2012 R2; Windows Server 2012 R2 (Server Core installation); and 5 more. Affected products named by the advisory: Windows Server 2016 (Server Core installation); Windows Server 2019 (Server Core installation); Windows Server 2022.