AUGUST 4, 2026
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Case File

CVE-2021-21787

HIGH · CVSS 8.8 EPSS 0.34%

Source: NVD + CISA KEV + EPSS (historical backfill) · Published 2021-07-07 · Last synced 2026-08-04

CyberRota Analysis

This is a high severity vulnerability with a CVSS score of 8.8. See the original NVD description below for full technical details.

CVE
CVE-2021-21787
Severity
HIGH
CVSS
8.8
EPSS
0.34%

Original NVD 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.

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