How severe is CVE-2021-33626?

CVE-2021-33626 has a CVSS 3.x base score of 7.8, 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-2021-33626 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (21st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-33626?

CVE-2021-33626 primarily affects Insyde Insydeh2o. In total, 17 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-33626?

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-2021-33626 published?

CVE-2021-33626 was published on 2021-10-01 and last updated on 2026-06-17.

CVE-2021-33626

CVE-2021-33626 is a high-severity vulnerability in Insyde Insydeh2o with a CVSS 3.x base score of 7.8. 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-829.

Key facts

Severity: High (CVSS 3.x base score 7.8)
CVSS v2: 4.6
EPSS exploit prediction: 0% (21st percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-829
Affected product: Insyde Insydeh2o
Published: 2021-10-01
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2021-33626?: 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.
How severe is CVE-2021-33626?: CVE-2021-33626 has a CVSS 3.x base score of 7.8, 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-2021-33626 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (21st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-33626?: CVE-2021-33626 primarily affects Insyde Insydeh2o. In total, 17 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-33626?: 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-2021-33626 published?: CVE-2021-33626 was published on 2021-10-01 and last updated on 2026-06-17.

References

Affected products (17)

cpe:2.3:o:insyde:insydeh2o:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:ruggedcom_apr1808_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:siemens:simatic_field_pg_m5_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:siemens:simatic_field_pg_m6_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:siemens:simatic_ipc127e_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:siemens:simatic_ipc227g_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:siemens:simatic_ipc277g_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:siemens:simatic_ipc327g_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:siemens:simatic_ipc377g_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:siemens:simatic_ipc427e_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:siemens:simatic_ipc477e_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:siemens:simatic_ipc477e_pro_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:siemens:simatic_ipc627e_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:siemens:simatic_ipc647e_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:siemens:simatic_ipc677e_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:siemens:simatic_ipc847e_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:siemens:simatic_itp1000_firmware:-:*:*:*:*:*:*:*

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