How severe is CVE-2021-21789?

CVE-2021-21789 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-21789 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (24th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-21789?

CVE-2021-21789 affects Iobit Advanced Systemcare Ultimate. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-21789?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2021-21789 published?

CVE-2021-21789 was published on 2021-07-07 and last updated on 2026-06-17.

CVE-2021-21789

CVE-2021-21789 is a high-severity vulnerability in Iobit Advanced Systemcare Ultimate with a CVSS 3.x base score of 8.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-782.

Key facts

Severity: High (CVSS 3.x base score 8.8)
CVSS v2: 4.6
EPSS exploit prediction: 0% (24th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-782
Affected product: Iobit Advanced Systemcare Ultimate
Published: 2021-07-07
Last modified: 2026-06-17

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 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.

Frequently asked questions

What is 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.
How severe is CVE-2021-21789?: CVE-2021-21789 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-21789 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (24th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-21789?: CVE-2021-21789 affects Iobit Advanced Systemcare Ultimate. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-21789?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-21789 published?: CVE-2021-21789 was published on 2021-07-07 and last updated on 2026-06-17.

References

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

Affected products (1)

cpe:2.3:a:iobit:advanced_systemcare_ultimate:14.2.0.220:*:*:*:*:*:*:*

More vulnerabilities in Iobit Advanced Systemcare Ultimate

CVE-2021-21788 — High (CVSS 8.8): A privilege escalation vulnerability exists in the way IOBit Advanced SystemCare Ultimate 14.2.0.220 driver handles…
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