CVE-2021-21787

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 0x9c40a0d8, the first dword passed in the input buffer is the device port to write to and the byte 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.

• CWE-782

• https://talosintelligence.com/vulnerability_reports/TALOS-2021-1254Exploit, Third Party Advisory
• https://talosintelligence.com/vulnerability_reports/TALOS-2021-1254Exploit, Third Party Advisory

Published

Jul 7, 2021

Last Modified

Jun 17, 2026

Status

Modified

• How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
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