A flaw has been found on Intel chips and hackers can exploit that vulnerability to gain access to your computer using the operating system. So far hackers exploited the vulnerability on Windows 7 64bit, Free BSD, NetBSD and there is a big chance to be exploited also in OS X. Attackers can use the flaw to execute code on your system with kernel privileges. AMD processors do not have that flaw as they don’t use the buggy SYSRET instruction. Affected operating systems are aware of that and they are preparing a fix, some of them were even pushed an update so there is a big chance that your system is safe (if your OS is up to date).
Intel CPU Vulnerability