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

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 (

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