Microsoft fixes known issue causing Windows Defender crashes
Microsoft resolved a bug in Windows Defender that caused crashes and 0xc0000005 access violation errors after a recent security update. The issue affected Windows 10 and Windows 11 devices, causing Defender scans to fail and the threat service to stop unexpectedly. The problem was addressed via a Microsoft Defender Antivirus signature update (version 1.457.236.0 or later), which is applied automatically or can be installed via Windows Update.
AI Analysis
Technical Summary
A bug introduced by a recent security update caused Windows Defender to crash on some Windows 10 and Windows 11 systems, resulting in 0xc0000005 access violation errors and failure of quick or full scans. Users reported error messages indicating the threat service stopped and needed restarting. Microsoft confirmed the issue and fixed it in a Defender Antivirus signature update version 1.457.236.0 or later. The fix is delivered automatically through signature updates or can be manually applied via Windows Update.
Potential Impact
The bug caused Windows Defender to crash and fail to perform malware scans, potentially reducing endpoint protection effectiveness temporarily on affected systems. However, there is no indication of exploitation or security bypass. The issue primarily caused service interruptions and scan failures rather than direct compromise.
Mitigation Recommendations
Microsoft has released a fix in Microsoft Defender Antivirus signature update version 1.457.236.0 or later. Users and administrators should ensure their systems have installed this update or have automatic updates enabled to receive the fix. No other action is required.
Microsoft fixes known issue causing Windows Defender crashes
Description
Microsoft resolved a bug in Windows Defender that caused crashes and 0xc0000005 access violation errors after a recent security update. The issue affected Windows 10 and Windows 11 devices, causing Defender scans to fail and the threat service to stop unexpectedly. The problem was addressed via a Microsoft Defender Antivirus signature update (version 1.457.236.0 or later), which is applied automatically or can be installed via Windows Update.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
A bug introduced by a recent security update caused Windows Defender to crash on some Windows 10 and Windows 11 systems, resulting in 0xc0000005 access violation errors and failure of quick or full scans. Users reported error messages indicating the threat service stopped and needed restarting. Microsoft confirmed the issue and fixed it in a Defender Antivirus signature update version 1.457.236.0 or later. The fix is delivered automatically through signature updates or can be manually applied via Windows Update.
Potential Impact
The bug caused Windows Defender to crash and fail to perform malware scans, potentially reducing endpoint protection effectiveness temporarily on affected systems. However, there is no indication of exploitation or security bypass. The issue primarily caused service interruptions and scan failures rather than direct compromise.
Defensive Guidance
Microsoft has released a fix in Microsoft Defender Antivirus signature update version 1.457.236.0 or later. Users and administrators should ensure their systems have installed this update or have automatic updates enabled to receive the fix. No other action is required.
Technical Details
- Classification
- {"confidence":0.3,"severitySource":"default","classifier":"rss-v2"}
- Article Source
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Threat ID: 6a85ed70acd9273b49693b18
Added to database: 08/19/2026, 17:52:48 UTC
Last enriched: 08/19/2026, 17:52:56 UTC
Last updated: 08/19/2026, 20:18:47 UTC
Views: 5
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