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Insydeh2oApplication · Insyde

CVE-2021-33627

HIGH · 8.2 CVSS v3.1 Published 2022-02-03
Fix available
A fix is available. Upgrade to 5.08.29 / 5.16.29 or later.
See remediation →
84/100
Remediation priority · High
Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
An issue was discovered in Insyde InsydeH2O Kernel 5.0 before 05.09.11, 5.1 before 05.17.11, 5.2 before 05.27.11, 5.3 before 05.36.11, 5.4 before 05.44.11, and 5.5 before 05.52.11 affecting FwBlockServiceSmm. Software SMI services that use the Communicate() function of the EFI_SMM_COMMUNICATION_PROTOCOL do not check whether the address of the buffer is valid, which allows use of SMRAM, MMIO, or OS kernel addresses.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

The vulnerability exists in InsydeH2O Kernel's FwBlockServiceSMM component where Software SMI services using the EFI_SMM_COMMUNICATION_PROTOCOL's Communicate() function fail to validate buffer address ranges. This allows unvalidated access to protected SMRAM (System Management RAM), MMIO regions, or OS kernel addresses, potentially enabling privilege escalation or code execution in SMM mode.

MitigationApply the appropriate InsydeH2O firmware update (kernel 5.0 to 05.09.11, 5.1 to 05.17.11, 5.2 to 05.27.11, 5.3 to 05.36.11, 5.4 to 05.44.11, or 5.5 to 05.52.11) after verifying the current version via the vendor's firmware update utility or documentation.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Insydeh2oApplication
Affected:>= 5.0, < 5.08.29>= 5.1, < 5.16.29>= 5.2, < 5.26.29>= 5.3, < 5.35.29
Simatic Field Pg M5 FirmwareOperating system
Affected:all versions
Simatic Field Pg M6 FirmwareOperating system
Affected:all versions
Simatic Ipc127e FirmwareOperating system
Affected:all versions
Simatic Ipc227g FirmwareOperating system
Affected:all versions
Simatic Ipc277g FirmwareOperating system
Affected:all versions
Simatic Ipc327g FirmwareOperating system
Affected:all versions
Simatic Ipc377g FirmwareOperating system
Affected:all versions

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
High
User interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify the UEFI/BIOS firmware vendor and version
    On Linux, run 'sudo dmidecode -s bios-version' and 'sudo dmidecode -s bios-vendor'. On Windows, run 'wmic bios get SMBIOSBIOSVersion, Manufacturer' in Command Prompt as Administrator.
    Affected if The vendor is Insyde and the version falls within any of these ranges: >=5.0 and <5.08.29, >=5.1 and <5.16.29, >=5.2 and <5.26.29, or >=5.3 and <5.35.29
  2. Check if running on an affected Siemens industrial device
    Identify the device model by running 'sudo dmidecode -s system-product-name' on Linux or 'wmic computersystem get model' on Windows.
    Affected if The device is a Siemens Simatic Field Pg M5, Simatic Field Pg M6, Simatic Ipc127e, Simatic Ipc227g, Simatic Ipc277g, Simatic Ipc327g, or Simatic Ipc377g (all versions are affected)
  3. Confirm InsydeH2O kernel version in firmware
    Use the vendor-provided firmware update utility or check the UEFI/BIOS setup utility's version information screen for the InsydeH2O kernel version string.
    Affected if The displayed InsydeH2O kernel version matches any of the vulnerable version ranges listed in step 1
  4. Verify FwBlockServiceSMM component presence
    Inspect the UEFI firmware image using tools like UEFI firmware tools (uefi-firmware-parser) or vendor-specific firmware dump utilities to search for the FwBlockServiceSMM driver module.
    Affected if The FwBlockServiceSMM module is present in the firmware and the version is within the affected ranges from step 1

You are affected if your system uses InsydeH2O firmware with a kernel version in any of the vulnerable ranges, or if it is any version of the listed Siemens Simatic devices, and the FwBlockServiceSMM component is present in the firmware.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 5.08.29 / 5.16.29 / 5.26.29 or later
Fixed in 5.08.295.16.295.26.29
Interim mitigation

Apply the appropriate InsydeH2O firmware update (kernel 5.0 to 05.09.11, 5.1 to 05.17.11, 5.2 to 05.27.11, 5.3 to 05.36.11, 5.4 to 05.44.11, or 5.5 to 05.52.11) after verifying the current version via the vendor's firmware update utility or documentation.

Recommended fix High confidence

InsydeH2O: upgrade to 05.09.11 (5.0), 05.17.11 (5.1), 05.27.11 (5.2), 05.36.11 (5.3), 05.44.11 (5.4), or 05.52.11 (5.5); Siemens devices: obtain vendor-specific patch

  1. 1. Identify the exact InsydeH2O version currently installed on the affected device by checking the BIOS/UEFI firmware version string
  2. 2. For InsydeH2O-based systems: Determine which version branch you are running (5.0, 5.1, 5.2, 5.3, 5.4, or 5.5) from the version number
  3. 3. Obtain the corresponding fixed firmware version from Insyde: for 5.0 branch upgrade to 05.09.11 or later, for 5.1 branch upgrade to 05.17.11 or later, for 5.2 branch upgrade to 05.27.11 or later, for 5.3 branch upgrade to 05.36.11 or later, for 5.4 branch upgrade to 05.44.11 or later, for 5.5 branch upgrade to 05.52.11 or later
  4. 4. Download the updated BIOS/UEFI firmware from the device manufacturer's support website (the OEM that uses InsydeH2O)
  5. 5. Apply the firmware update following the manufacturer's specific update procedure, which typically involves flashing the BIOS through a USB drive or within the operating system
  6. 6. For Siemens Simatic devices (Field Pg M5/M6, IPC127e, IPC227g, IPC277g, IPC327g, IPC377g): contact Siemens support or visit their product security portal to obtain device-specific firmware patches that address this vulnerability
Caveat BIOS firmware updates carry risk of bricking the device if interrupted or applied incorrectly; ensure stable power and follow OEM flashing instructions exactly

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Insydeh2o Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA2.0 h
20.0 hours of engineering $3,500
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-33627 in production — separate from our analysis above.

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  • Version or environment caveats, and links to real fixes
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