What’s Vulnerable › Vulnerabilities

CVE-2021-33626

• Severity: high (CVSS 7.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2021-10-01 · updated 2026-08-11
• Weakness: CWE-829

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.

Affected products

• Insydeh2O: from 5.3 before 5.34.44; from 5.2 before 5.25.44; from 5.1 before 5.16.25; from 5.4 before 5.42.44; from 5.3 before 5.35.25; from 5.2 before 5.26.25 — fixed in 5.16.25, 5.25.44, 5.26.25, 5.34.44, 5.35.25, 5.42.44
• 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

How to fix

Upgrade to a fixed version: Insydeh2O 5.16.25, 5.25.44, 5.26.25, 5.34.44. Check the vendor advisory for mitigations.

References

• https://cert-portal.siemens.com/productcert/pdf/ssa-306654.pdf
• https://security.netapp.com/advisory/ntap-20220216-0006/
• https://www.insyde.com/security-pledge
• https://www.insyde.com/security-pledge/SA-2021001
• https://cert-portal.siemens.com/productcert/pdf/ssa-306654.pdf
• https://security.netapp.com/advisory/ntap-20220216-0006/
• https://www.insyde.com/security-pledge
• https://www.insyde.com/security-pledge/SA-2021001
• https://www.kb.cert.org/vuls/id/796611
• https://cert-portal.siemens.com/productcert/html/ssa-306654.html

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