Nightmare Eclipse has released a new zero-day vulnerability exploit called GreatXML, which allows unrestricted access to BitLocker volumes on Windows systems that have previously run a Microsoft Defender Offline scan. This discovery was made in four hours and adds to Nightmare Eclipse's total of eight zero-day vulnerabilities. Microsoft is investigating the claims related to another exploit, RoguePlanet, but has not commented on GreatXML or provided a patch timeline. Nightmare Eclipse, rumored to be a former Microsoft employee, has faced backlash from the security community for previous disclosures and has vowed to continue releasing vulnerabilities. Security expert Will Dormann has raised concerns about the practicality of the GreatXML exploit, noting that it requires administrative access and questioning the accuracy of the instructions provided by Nightmare.