GoKawiilMicrosoft patches false 'Defender Antivirus is off' alert bug
Microsoft has fixed a glitch that made the Windows Security app falsely warn users that Defender Antivirus was disabled, even though it was running normally. The fix arrived in Defender Antivirus update version 4.18.26080.4, released September 17, after the problem had persisted since at least June in Windows Insider builds.
GoKawiil's interpretation of the reporting above, not reported fact.
False security warnings can erode user trust and prompt unnecessary troubleshooting or support calls, especially across widely deployed systems like Windows 11 and Windows Server 2025. This is part of a pattern of update-related false alerts from Microsoft this year, including bogus BitLocker and Firewall warnings, raising questions about the company's update testing processes.
- The bug falsely showed Defender Antivirus as turned off despite it functioning correctly.
- It affected all supported Windows client and server versions since at least June 2025.
- This is the latest in a series of 2025 update-related false alert issues from Microsoft.
Source: bleepingcomputer.com, 2026-09-18
Published there as: “Microsoft fixes bug behind ‘Defender Antivirus is turned off’ alerts”
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