Nightmare Eclipse Drops Windows Zero-Day Exploit ‘ShieldBreak’
Security researcher Nightmare Eclipse has dropped a fresh zero-day exploit leading to privilege escalation on Windows.
Also known as Chaotic Eclipse, the disgruntled researcher released multiple zero-day exploits targeting Microsoft products over the past several months, usually right after the Patch Tuesday security updates.
Right on cue, the new proof-of-concept (PoC) exploit, dubbed ShieldBreak, was published on August 2026 Patch Tuesday. It targets a vulnerability in Microsoft Defender, allowing any user to gain System privileges.
According to Nightmare Eclipse, the exploit is a RoguePlanet patch bypass, works on the latest Windows 11 versions and on Windows Server 2025, and likely impacts Windows 10 machines as well.
Tracked as CVE-2026-50656, RoguePlanet is a race condition flaw in Defender that Nightmare Eclipse dropped as a zero-day on June 9. Microsoft acknowledged the exploit on June 16 and released fixes for it on July 9.
Per the analysisof Tharros Labs’s...
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