Microsoft Server Security Advisories & CVEs
1355 advisories tracked · Microsoft Security Update Guide (MSRC) · direct feeds checked every minute; rate-limited backstops use a safe source cadence
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Official 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 advisories
Medium [CVE-2026-0390] UEFI Secure Boot Security Feature Bypass Vulnerability
Reliance on untrusted inputs in a security decision in Windows Boot Loader 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 1 more. Affected products named by the advisory: Windows Server 2022.
Medium [CVE-2026-32085] Remote Procedure Call Information Disclosure Vulnerability
Exposure of sensitive information to an unauthorized actor in Windows Remote Procedure Call allows an authorized attacker to disclose information 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).
Medium [CVE-2026-32081] Package Catalog Information Disclosure Vulnerability
Exposure of sensitive information to an unauthorized actor in Windows File Explorer allows an authorized attacker to disclose information 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).
Medium [CVE-2026-27931] Windows GDI Information Disclosure Vulnerability
Out-of-bounds read in Windows GDI allows an unauthorized attacker to disclose information 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).
Medium [CVE-2026-26175] Windows Boot Manager Security Feature Bypass Vulnerability
Use of uninitialized resource in Windows Boot Manager allows an unauthorized attacker to bypass a security feature with a physical attack. 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).
Medium [CVE-2026-26155] Microsoft Local Security Authority Subsystem Service Information Disclosure Vulnerability
Microsoft Local Security Authority Subsystem Service Information Disclosure Vulnerability 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).
Medium [CVE-2026-23670] Windows Virtualization-Based Security (VBS) Security Feature Bypass Vulnerability
Untrusted pointer dereference in Windows Virtualization-Based Security (VBS) Enclave 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).
Medium [CVE-2026-20945] Microsoft SharePoint Server Spoofing Vulnerability
Improper neutralization of input during web page generation ('cross-site scripting') in Microsoft Office SharePoint allows an authorized attacker to perform spoofing over a network. Affected products named by the advisory: Microsoft SharePoint Enterprise Server 2016; Microsoft SharePoint Server 2019; Microsoft SharePoint Server Subscription Edition.
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).