Hackers are abusing unpatched Windows security flaws to hack into organizations

2026-04-20

Threat actors are exploiting unpatched Windows Defender vulnerabilities (BlueHammer, UnDefend, and RedSun) to achieve administrative access in active attacks. Despite a public disclosure of exploit code by researcher Chaotic Eclipse, only BlueHammer has been patched. Organizations are advised to promptly secure their Windows Defender deployments.