Three Microsoft Defender Zero-Days Actively Exploited; Two Still Unpatched

Overview

Huntress is warning that threat actors are exploiting three recently disclosed security flaws in Microsoft Defender to gain elevated privileges in compromised systems. The activity involves the exploitation of three vulnerabilities that are codenamed BlueHammer (requires GitHub sign-in), RedSun, and UnDefend, all of which were released as zero-days by a researcher known as Chaotic Eclipse (

Key Developments

This reflects an evolving cybersecurity situation.

Technical Details

Attackers may use automation and vulnerabilities.

Impact & Risks

Potential disruption and data exposure.

Conclusion

Organizations must stay vigilant.

Read more: https://thehackernews.com/2026/04/three-microsoft-defender-zero-days.html