Critical BlueHammer Zero-Day Turns Windows Defender Into Attack Vector

A critical zero-day vulnerability in Windows Defender has been publicly disclosed without a patch, exposing billions of Windows machines to immediate privilege escalation attacks. The exploit, named BlueHammer, chains five legitimate Windows components to elevate low-privileged accounts directly to SYSTEM access. The controversial disclosure comes after the researcher alleged Microsoft violated a responsible disclosure agreement, highlighting growing tensions in the security research community over coordinated vulnerability management practices.