ShieldBreak: The Windows Defender 0-Day with No Patch - And What to Do About It.
In mid-June 2026, Microsoft acknowledged RoguePlanet, a privilege-escalation flaw in the Microsoft Malware Protection Engine (mpengine.dll), the scanning engine behind Windows Defender. Microsoft rated it "Exploitation More Likely" on its Exploitability Index and assigned a CVSS score of 7.8. Microsoft shipped a fix in Malware Protection Engine version 1.1.26060.3008 during its July 2026 patch cycle.