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Hackers Exploit Microsoft Defender Flaws, Patches Incomplete

4/18/2026

Summary

Story summary

Hackers are exploiting three Microsoft Defender vulnerabilities—BlueHammer, UnDefend, and RedSun—disclosed by Chaotic Eclipse, which allow attackers to gain elevated privileges on compromised systems.
Microsoft has patched BlueHammer, while fixes for UnDefend and RedSun are still pending.
Huntress reports these flaws have been weaponized since April 10, 2026.
The broader effect is that exploit code published by researchers can fuel attacks, complicating vulnerability disclosures and raising risk for affected organizations.

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Story summary

Hackers are exploiting three Microsoft Defender vulnerabilities—BlueHammer, UnDefend, and RedSun—disclosed by Chaotic Eclipse, which allow attackers to gain elevated privileges on compromised systems.
Microsoft has patched BlueHammer, while fixes for UnDefend and RedSun are still pending.
Huntress reports these flaws have been weaponized since April 10, 2026.
The broader effect is that exploit code published by researchers can fuel attacks, complicating vulnerability disclosures and raising risk for affected organizations.