An anonymous researcher known as Nightmare-Eclipse has revealed two new vulnerabilities affecting Windows systems, named YellowKey and GreenPlasma, shortly after Microsoft's latest Patch Tuesday update. YellowKey is a "BitLocker bypass" that allows attackers with physical access to gain unrestricted shell access to protected machines. Experts have expressed concerns about YellowKey's potential to transform laptop theft into a serious breach notification scenario, and suggested mitigations such as implementing a BitLocker PIN and a BIOS password lock. Nightmare-Eclipse has also hinted that YellowKey could function as a backdoor allegedly introduced by Microsoft, although this claim remains unsubstantiated. GreenPlasma is a privilege escalation flaw for which partial exploit code has been released, but it currently triggers a User Account Control (UAC) consent prompt, requiring attackers to invest time in weaponizing it. There is no known mitigation for GreenPlasma, making it crucial for organizations to patch their systems promptly once Microsoft addresses the issue. Nightmare-Eclipse has previously disclosed five zero-day vulnerabilities this year, including BlueHammer, and has characterized their actions as a response to a perceived violation of trust. The researcher has indicated the existence of a "dead man's switch," suggesting that more disclosures could follow if their demands are not met.