Microsoft Windows 8.1, Windows Server 2012 Gold and R2, Windows RT 8.1, Windows 10 Gold, 1511, and 1607, and Windows Server 2016 allow physically proximate attackers to bypass the Secure Boot protection mechanism via a crafted boot policy, aka "Secure Boot Component Vulnerability."
https://h20566.www2.hp.com/portal/site/hpsc/public/kb/docDisplay?docId=emr_na-c05340049
https://docs.microsoft.com/en-us/security-updates/securitybulletins/2016/ms16-140