CVE-2021-21787

high

Description

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.

References

https://talosintelligence.com/vulnerability_reports/TALOS-2021-1254

Details

Source: Mitre, NVD

Published: 2021-07-07

Updated: 2026-06-17

Risk Information

CVSS v2

Base Score: 4.6

Vector: CVSS2#AV:L/AC:L/Au:N/C:P/I:P/A:P

Severity: Medium

CVSS v3

Base Score: 8.8

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

Severity: High

EPSS

EPSS: 0.00146