CVE-2021-33626

Name: CVE-2021-33626
Creator: NVD / NIST
Published: 2021-10-01T03:15:06.593+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 7.8/10EPSS 0.30%

Last modified Jun 17, 2026

CVE-2021-33626 is a high-severity vulnerability rated 7.8/10 on the CVSS scale. 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.. EPSS estimates a 0.30% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1

7.8/10

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

EPSS Probability

0.30%

21.3th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-829

Affected Software

Vendor	Product	Versions
Insyde	Insydeh2o	>= 5.3, < 5.34.44
Insyde	Insydeh2o	>= 5.2, < 5.25.44
Insyde	Insydeh2o	>= 5.1, < 5.16.25
Insyde	Insydeh2o	>= 5.4, < 5.42.44
Insyde	Insydeh2o	>= 5.3, < 5.35.25
Insyde	Insydeh2o	>= 5.2, < 5.26.25
Insyde	Insydeh2o	>= 5.4, < 5.43.25
Siemens	Ruggedcom Apr1808 Firmware	All versions
Siemens	Simatic Field Pg M5 Firmware	All versions
Siemens	Simatic Field Pg M6 Firmware	All versions
Siemens	Simatic Ipc127e Firmware	All versions
Siemens	Simatic Ipc227g Firmware	All versions
Siemens	Simatic Ipc277g Firmware	All versions
Siemens	Simatic Ipc327g Firmware	All versions
Siemens	Simatic Ipc377g Firmware	All versions
Siemens	Simatic Ipc427e Firmware	All versions
Siemens	Simatic Ipc477e Firmware	All versions
Siemens	Simatic Ipc477e Pro Firmware	All versions
Siemens	Simatic Ipc627e Firmware	All versions
Siemens	Simatic Ipc647e Firmware	All versions
Siemens	Simatic Ipc677e Firmware	All versions
Siemens	Simatic Ipc847e Firmware	All versions
Siemens	Simatic Itp1000 Firmware	All versions

References

https://cert-portal.siemens.com/productcert/pdf/ssa-306654.pdfThird Party Advisory
https://security.netapp.com/advisory/ntap-20220216-0006/Third Party Advisory
https://www.insyde.com/security-pledgeVendor Advisory
https://www.insyde.com/security-pledge/SA-2021001Vendor Advisory
https://cert-portal.siemens.com/productcert/pdf/ssa-306654.pdfThird Party Advisory
https://security.netapp.com/advisory/ntap-20220216-0006/Third Party Advisory
https://www.insyde.com/security-pledgeVendor Advisory
https://www.insyde.com/security-pledge/SA-2021001Vendor Advisory
https://www.kb.cert.org/vuls/id/796611

Timeline

Published: Oct 1, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-33626?

How severe is CVE-2021-33626?

CVE-2021-33626 has a CVSS score of 7.8/10 (HIGH severity). The EPSS model estimates a 0.30% probability of exploitation in the next 30 days.

How do I fix CVE-2021-33626?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-33626?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST