The zero-day vulnerabilities are CVE-2019-1214 and CVE-2019-1215. The first affects the Windows Common Log File System (CLFS) and it allows an authenticated attacker with regular user privileges to escalate permissions to administrator. The security hole was reported to Microsoft by a researcher from the Qihoo 360 Vulcan Team, but no details appear to have been released about the attacks exploiting the vulnerability.
It’s worth noting that while all supported versions of Windows appear to be affected by this weakness, Microsoft says exploitation is unlikely against the latest versions of the operating system.
