Microsoft starts fix for Defender zero-day "ShieldBreak" Microsoft says it is preparing a patch for CVE-2026-69414, a Microsoft Defender elevation-of-privilege flaw publicly dubbed ShieldBreak. The PoC released by Nightmare Eclipse reportedly lets a local low-privilege user gain SYSTEM on fully patched Windows 11 and Windows Server systems when Defender is enabled. Microsoft began tracking the issue three days after disclosure.

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-69414