New Windows Zero-Day Claims BitLocker Bypass Amid Microsoft Disclosure Fight

Security researcher releases and public proof-of-concept disclosures have spotlighted two Windows zero-day issues: GreatXML, alleged to bypass BitLocker by manipulating the recovery partition and rebooting into the Windows Recovery Environment, and RoguePlanet, a Microsoft Defender race-condition exploit that researchers validated can spawn a SYSTEM prompt on Windows 10/11. GreatXML’s practicality is disputed (may require admin access), RoguePlanet was reported as effective on patched consumer OS builds but not servers, and organizations are urged to apply June 2026 updates, review Defender Offline and BitLocker recovery protections, and prioritize high-risk endpoints.