Is CVE-2021-33626 in the CISA KEV catalog?

No. CVE-2021-33626 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2021-33626?

CVE-2021-33626 has a CVSS v3 base score of 7.8 (HIGH).

What is the EPSS score for CVE-2021-33626?

CVE-2021-33626 has an EPSS score of 0.30% (21th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2021-33626?

Upgrade insydeh2o to 5.43.25 or later.

CVE & CISA-KEV Catalog

CVE-2021-33626

HIGH

7.8

CVSS v3

NVD

Description

A vulnerability exists in SMM (System Management Mode) branch that registers a SWSMI handler that does not sufficiently check or validate the allocated buffer pointer(QWORD values for CommBuffer). This can be used by an attacker to corrupt data in SMRAM memory and even lead to arbitrary code execution.

CWE-829

How to fix

Remediation Available

insydeh2oNVD

Affected:>= 5.4, < 5.43.25Fixed in:5.43.25CVE-2021-33626derived from NVD

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorLocal

Attack ComplexityLow

Privileges RequiredLow

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

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

Exploit Intelligence

0.30%probability of exploitation in 30 days

21stpercentile

Low risk: more likely to be exploited than 21% of all known CVEs.

References

Vendor Advisory2

Third-Party Advisory2

Other references1

kb.cert.org

Related Vulnerabilities

Other CWE-829 vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2018-17246	Critical	9.8	82%	-	Fix
CVE-2024-5762	High	8.1	72%	-	-
CVE-2018-7422	High	7.5	63%	-	-
CVE-2023-2249	High	8.8	61%	-	-
CVE-2025-32463	Critical	9.3	47%	KEV	Fix
CVE-2024-38476	Critical	9.8	42%	-	Fix

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2025-11-04.