CVE-2021-21788: Iobit Advanced Systemcare Ultimate

High severity, CVSS 8.8. EPSS: 0.3% chance of exploitation in the next 30 days.

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 0x9c40a0dc, the first dword passed in the input buffer is the device port to write to and the word at offset 4 is the value to write via the OUT instruction. The OUT instruction can write one byte to the given I/O device port, potentially leading to escalated privileges of unprivileged users. A local attacker can send a malicious IRP to trigger this vulnerability.

Affected products

• Iobit Advanced Systemcare Ultimate: version 14.2.0.220 only

Published 2021-07-07. Last modified 2026-06-17.