A flaw exists in the way that a specific instruction is handled on some types of Intel 64-bit chips that could open up some operating systems and types of virtualization software to attacks. Attackers could execute malicious code via kernel privileges or launch a local privilege escalation attack. The flaw has already been exploited on Windows 7, FreeBSD, NetBSD and there’s a chance Apple s OS X may also be vulnerable, according to a blog on Xen.org, an open source community.
Source: https://threatpost.com/intel-processor-sysret-vulnerability-affecting-some-64-bit-systems-061812/76705/