Vulnerability CVE-2021-21789

A privilege escalation vulnerability exists in the way IOBit Advanced SystemCare Ultimate 14.2.0.220 driver handles Privileged I/O write requests. During IOCTL 0x9c40a0e0, the first dword passed in the input buffer is the device port to write to and the dword at offset 4 is the value to write via the OUT instruction. A local attacker can send a malicious IRP to trigger this vulnerability.