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BleepingComputer
New Microsoft Defender 'ShieldBreak' zero-day grants SYSTEM privileges
Security researcher Nightmare Eclipse has disclosed a new Microsoft Defender zero-day exploit called 'ShieldBreak,' which exploits a vulnerability that allows gaining SYSTEM privileges on patched Windows systems. The exploit is reportedly a bypass of an earlier flaw known as RoguePlanet. Microsoft's handling of vulnerability disclosures and the ongoing dispute with the researcher has further raised security concerns surrounding its Defender software. Experts have noted the exploit's successful tests, intensifying scrutiny on Microsoft’s patching strategies and response mechanisms.
Act nowConfidence: HighImmediate horizonCybersecurity risk: High
Published 12 Aug 2026, 10:50 UTC2 min read
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Summary
TL;DR
- New zero-day exploit 'ShieldBreak' allows SYSTEM privileges on Windows systems.
- Exploits previously disclosed vulnerabilities, highlighting patch failures.
- Microsoft threatened legal action against the researcher sharing the exploit.
- The exploit has a 100% success rate in tested environments.
- Ongoing disputes between Microsoft and cybersecurity researchers continue.
Interesting facts
- 'ShieldBreak' bypasses the patch for the RoguePlanet vulnerability.
- The exploit is part of a series of reported vulnerabilities by the same researcher.
- Microsoft has faced ongoing criticism regarding its bug bounty and vulnerability handling procedures.