Google’s Project Zero has discovered and published a buffer overflow vulnerability in the Windows Kernel Cryptography Driver. The exploit doesn’t affect the cryptography, but allows attackers to escalate system privileges:
Attackers were combining an exploit for it with a separate one targeting a recently fixed flaw in Chrome. The former allowed the latter to escape a security sandbox so the latter could execute code on vulnerable machines.
The vulnerability is being exploited in the wild, although Microsoft says it’s not being exploited widely. Everyone expects a fix in the next Patch Tuesday cycle.