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

Microsoft patches 398 flaws, including exploited CVE-2026-68820 that lets local attackers reach SYSTEM, plus four unauthenticated 9.8 RCEs.

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