Nightmare Eclipse has released a new Microsoft Defender zero-day exploit named "ShieldBreak" after Microsoft released the August 2026 Patch Tuesday security updates.

This is the latest zero-day released by security researcher Nightmare Eclipse, despite Microsoft publicly threatening to take legal action against them.

The 'ShieldBreak' flaw can let an attacker use Windows Defender to escalate their privileges on the OS. Microsoft previously threatened legal action against the researcher, Nightmare Eclipse.

ShieldBreak is a claimed patch bypass for Defender flaw CVE-2026-50656, with a PoC tested on Windows 11 25H2 and Server 2025.

The PoC posted by Nightmare Eclipse, who has been feuding with Microsoft for months, enables an attacker with any level of access to gain system-level privileges.

Microsoft on Tuesday released fixes for two high-severity zero-days that were disclosed by a researcher who has been locked in a testy beef with the software giant. Nightmare Eclipse, the pseudonym ...

Microsoft has released security patches to address a Windows zero-day vulnerability known as "LegacyHive," disclosed after the July 2026 Patch Tuesday. The security flaw was disclosed by a security ...