Patch Tuesday

Tech Optimizer
April 21, 2026
Microsoft has stated that third-party antivirus software is not necessary for Windows 11, as its built-in antivirus solution, Windows Defender, is sufficient for most users. This assertion was made public on April 9, when Microsoft declared Windows 11 the most secure version of its operating system. Windows Defender is effective when users regularly install Security Intelligence Updates, apply monthly Patch Tuesday updates, and activate SmartScreen for filtering harmful downloads. While third-party antivirus solutions may be beneficial in certain scenarios, such as enterprise environments or for users seeking additional features, Microsoft advises relying on a single real-time antivirus solution, which is typically Windows Defender. Microsoft Defender is a comprehensive protection stack that includes real-time scanning, cloud-delivered protection, and automatic updates. Independent tests have shown that Microsoft Defender achieves high protection rates, comparable to leading paid antivirus solutions. The built-in Windows Security application includes features like SmartScreen, Smart App Control, and ransomware protection, providing extensive coverage without additional costs. The consensus is that most users will not need third-party antivirus software in 2026, as Windows Security offers robust protection against modern threats.
Winsage
April 20, 2026
Microsoft has released emergency updates for various versions of Windows Server due to issues arising from the April 2026 Patch Tuesday security updates. A significant problem was a reboot loop affecting domain controllers caused by crashes of the Local Security Authority Subsystem Service (LSASS), which disrupted authentication services. This issue was especially problematic during the setup of new domain controllers. Additionally, some Windows Server 2025 systems encountered difficulties in installing the security update KB5082063. The out-of-band update (KB5091157) for Windows Server 2025 addresses both the installation failure and the domain controller restart issue. Other updates targeting the domain controller restart problem were released for additional supported Windows Server versions. Microsoft has introduced an out-of-band update for seven versions, including KB5091157 for Windows Server 2025 and KB5091571 for Windows Server, version 23H2. Furthermore, some Windows Server 2025 devices may boot into BitLocker recovery mode after the update, requiring users to enter a BitLocker recovery key.
Winsage
April 20, 2026
Microsoft has confirmed that some administrators are experiencing difficulties installing the KB5082063 security update on Windows Server 2025. This month's Patch Tuesday updates have caused certain Windows servers, especially those with domain controller roles, to enter a restart loop due to failures in the Local Security Authority Subsystem Service (LSASS). Microsoft has released emergency out-of-band updates, including KB5091157 for Windows Server 2025, to address both the installation failure and the restart issues. Additionally, some Windows Server 2025 devices may boot into BitLocker recovery mode after installing the KB5082063 update. A bug affecting Windows Server 2019 and Windows Server 2022 that caused unexpected upgrades to Windows Server 2025 has also been resolved. Microsoft has issued various emergency updates throughout the year to address other issues, including a Bluetooth device visibility bug and vulnerabilities in the Routing and Remote Access Service (RRAS).
Winsage
April 19, 2026
Microsoft is updating Windows 11 by improving File Explorer, focusing on performance and user experience. The latest release, Windows 11 Build 26200.8313, shows File Explorer loading faster and eliminating white flashes in dark mode. This build is currently for Windows Insiders, with public availability expected in April 2026 and further updates in May 2026. The update enhances speed, manages themes better, and adds support for new archive formats like cpio, uu, xar, and nupkg. Reliability improvements have reduced crashes related to explorer.exe, and new features include a preview option for internet-downloaded files, a redesigned search bar, and immediate reflection of folder view preferences.
Winsage
April 18, 2026
A series of updates have been released, focusing on system integrity and performance. Users should perform verification tasks, including installing, uninstalling, and repairing MSI packages, connecting and disconnecting cloud sync providers, and enrolling devices in Intune or MDM solutions. The Common Log File System driver (clfs.sys) is receiving a follow-up patch, along with updates to Storage Spaces (spaceport.sys) and app isolation file system drivers (bfs.sys, wcifs.sys). Users should also run Windows Update installation and rollback cycles, install and uninstall applications, and verify data integrity through backup solutions. For Storage Spaces, creating a pool with mirrored and thin virtual disks and ensuring clean deletion is necessary. April's updates for Office target MSI editions, including Excel 2016 (KB5002860), PowerPoint 2016 (KB5002808), Office 2016 shared libraries (KB5002859), and SharePoint Server editions from 2016 to 2019. These updates do not apply to Click-to-Run deployments like Microsoft 365 Apps. Users should validate complex Excel workbooks, PowerPoint presentations, SharePoint document libraries, and the functionality of Office add-ins. Testing for two High Risk components is essential: changes to Kerberos may disrupt services using RC4 keytabs, and the Remote Desktop client update requires validation of clipboard functionality, printer redirection, and session reconnection. Validating Secure Boot and BitLocker is critical as CVE-2023-24932 key rolling progresses. Additionally, cloud sync testing is important due to five patches to the Projected File System driver, and regression testing is needed for dual afd.sys updates and VPN/IPsec patches across remote-access infrastructure. Office updates are limited to MSI editions.
Winsage
April 17, 2026
Microsoft has acknowledged that the April 2026 security update for Windows Server, patch KB5082063, has caused significant disruptions for some enterprise domain controllers, leading to continuous reboot cycles in non-Global Catalog domain controllers used in Privileged Access Management (PAM) deployments. This has resulted in the unavailability of Active Directory authentication and directory services on affected servers. Additionally, the installation of KB5082063 may fail on some Windows Server 2025 systems. This issue marks the third consecutive year that April security updates have caused problems for Windows Server domain controllers. In previous years, Microsoft issued emergency fixes for similar issues, including crashes and complications with NTLM authentication. Administrators currently have limited options, including delaying the update, isolating a test domain controller, or engaging with Microsoft Support for tailored mitigation steps.
Winsage
April 17, 2026
Microsoft has programmed its Edge browser to automatically launch after a Windows 11 update, displaying a page that informs users their update is complete and prompts them to explore new features. This page lacks a close button, directing users to click a blue "Next" button to proceed. The features highlighted include the reinstatement of the taskbar clock, the ability to pin Emojis to the taskbar, Copilot's document summarization, the Snipping Tool's Quick markup, and AI actions in File Explorer's context menu. Users can provide feedback via like and dislike buttons, but these do not close the page. Windows 11 also includes pre-installed Get Started and Get Help apps that could showcase features instead of redirecting users to Edge. Edge, built on the Chromium engine, supports all extensions from that platform and includes features like AI tab organizer, Vertical Tabs, and Immersive Reader.
Winsage
April 16, 2026
Users have reported issues with Windows 11 update KB5083769, which has triggered BitLocker recovery key prompts, locking some users out of their PCs. Microsoft acknowledged that the problem mainly affects corporate devices with specific BitLocker Group Policy settings. The issue is limited to systems where BitLocker is enabled, certain Group Policy configurations are set, and the Secure Boot State PCR7 Binding is “Not Possible.” Affected users need to enter their BitLocker recovery key or contact IT support for assistance. Microsoft has also provided guidance for IT departments to perform a Known Issue Rollback to remove the problematic updates, though this may expose systems to vulnerabilities.
Tech Optimizer
April 16, 2026
A security researcher named Chaotic Eclipse has discovered a significant vulnerability in Microsoft Defender that could allow hackers to gain administrative access to systems running Windows 10, Windows 11, and Windows Server. The vulnerability arises from Windows Defender's behavior of rewriting detected malicious files back to their original location instead of removing them, which can be exploited to overwrite system files and grant unauthorized users elevated privileges. This issue remains unaddressed by Microsoft, leaving millions of users vulnerable. Although there is no current evidence of active exploitation, the situation could change. Users are advised to consider additional antivirus solutions for enhanced security.
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