A 0-day bug on the Windows platform is affecting win32k.sys (a critical component of the Windows kernel) The vulnerability is triggered by a buffer overflow in the kernel file, which allows code to bypass UAC on Windows Vista and Windows 7. A working proof of concept has been publicly available for a few hours on an extremely popular programming website. We are aware of the situation and were working on a generic detection scheme to prevent malicious code from reaching the kernel.”]
Source: https://www.bitdefender.com/blog/hotforsecurity/windows-kernel-bug-may-bypass-user-account-control/