A security researcher named Chaotic Eclipse (aka INFINITE NIGHTMARE, MSNightmare, and Nightmare-Eclipse) has released a proof-of-concept (PoC) for a new Microsoft zero-day called ShieldBreak This article explores shieldbreak exploit allows. . This exploit allows an attacker to spawn a shell with SYSTEM-level privileges, enabling them to run arbitrary code or perform unauthorized actions.
Soon after, Chaotic Eclipse revealed that Microsoft’s recently implemented “defense-in-depth updates” designed to address CVE-2026-50656 can cause Defender to leak 8 bytes of data when attempting to open files in specific scenarios on Windows 11 25H2 and Windows Server 2025.
Meanwhile, ShieldBreak has been assessed as a full patch bypass for CVE-2026-50656, with the researcher claiming that “Microsoft failed to properly patch the RoguePlanet vulnerability.” The PoC was successfully tested on the latest version of Windows 11 25H2 (+Canary channel) and Windows Server 2025, with a reported 100% success rate. One of the patches addresses a privilege escalation vulnerability involving CVE-2026-62832 (CVSS score: 7.8), a Windows User Profile Service flaw that was disclosed by Chaotic Eclipse last month under the name LegacyHive. Since adding CVE-2026-68820, the U.S. Cybersecurity and Infrastructure Security Agency (CISA) has expanded its Known Exploited Vulnerabilities (KEV) catalog, mandating that federal agencies implement the necessary fixes by August 25, 2026.
