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Insydeh2oApplication · Insyde

CVE-2021-41837

HIGH · 8.2 CVSS v3.1 Published 2022-02-03
Fix available
A fix is available. Upgrade to 5.08.41 / 5.16.41 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 AhciBusDxe in the kernel 5.0 through 5.5 in Insyde InsydeH2O. Because of an Untrusted Pointer Dereference that causes SMM memory corruption, an attacker may be able to write fixed or predictable data to SMRAM. Exploiting this issue could lead to escalating privileges to SMM.

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 · moderate confidence

A flaw in AhciBusDxe driver in InsydeH2O kernel 5.0-5.5 allows an untrusted pointer to be dereferenced, corrupting SMM memory. Attackers can write predictable data to SMRAM, achieving privilege escalation to System Management Mode.

MitigationApply vendor-supplied firmware update addressing the untrusted pointer dereference in AhciBusDxe; until patched, monitor system for unauthorized firmware modifications.

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, < 5.08.41>= 5.1, < 5.16.41>= 5.2, < 5.26.41>= 5.3, < 5.35.41>= 5.4, < 5.43.41>= 5.5, < 5.51.41
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 system firmware vendor and version
    Use system utilities such as dmidecode, inxi, or the system's BIOS/UEFI information page to determine the firmware vendor and version. Look for 'InsydeH2O' or 'Insyde' as the firmware provider and note the exact version number displayed.
    Affected if The firmware is from Insyde and the version falls within any of these ranges: >=5.0 to <5.08.41, >=5.1 to <5.16.41, >=5.2 to <5.26.41, >=5.3 to <5.35.41, >=5.4 to <5.43.41, or >=5.5 to <5.51.41.
  2. Confirm AhciBusDxe driver presence in firmware
    Inspect the UEFI firmware image or use tools like uefi-firmware-parser, chipsec, or the system's firmware dump to identify if the AhciBusDxe driver is included in the firmware.
    Affected if The AhciBusDxe driver is present in the UEFI firmware build.
  3. Identify Siemens Simatic device model and firmware
    Check the device model number through system information, dmidecode, or physical device labeling. Retrieve the current firmware version from the device's system information or BIOS setup.
    Affected if The device is a Siemens Simatic Field Pg M5, M6, Simatic Ipc127e, Ipc227g, Ipc277g, Ipc327g, or Ipc377g, regardless of firmware version.
  4. Check for SMM memory corruption indicators
    Review system logs, SMM memory access attempts, or use memory forensics tools to look for anomalies in SMRAM or indicators of untrusted pointer dereference activity related to AHCI driver operations.
    Affected if SMM memory shows unexpected modifications or the AHCI driver is observed making abnormal SMM calls.

A system is affected if it runs InsydeH2O firmware version within the specified vulnerable ranges and includes the AhciBusDxe driver, or if it is any Siemens Simatic device from the listed models regardless of version.

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 5.08.41 / 5.16.41 / 5.26.41 or later
Fixed in 5.08.415.16.415.26.41
Interim mitigation

Apply vendor-supplied firmware update addressing the untrusted pointer dereference in AhciBusDxe; until patched, monitor system for unauthorized firmware modifications.

Recommended fix High confidence

InsydeH2O version 5.08.41, 5.16.41, 5.26.41, or 5.35.41 (depending on your current branch); Siemens firmware updates from cert-portal.siemens.com

  1. 1. Identify the current InsydeH2O kernel version by checking the UEFI firmware version on the affected device.
  2. 2. For InsydeH2O versions >= 5.0, upgrade to version 5.08.41 or later.
  3. 3. For InsydeH2O versions >= 5.1, upgrade to version 5.16.41 or later.
  4. 4. For InsydeH2O versions >= 5.2, upgrade to version 5.26.41 or later.
  5. 5. For InsydeH2O versions >= 5.3, upgrade to version 5.35.41 or later.
  6. 6. For Siemens Simatic devices, apply vendor-provided firmware updates that incorporate the InsydeH2O security patch. Check cert-portal.siemens.com for device-specific updates.
  7. 7. After firmware update, verify the UEFI/BIOS version matches the expected patched version.
Caveat Firmware updates may require physical access to the device; some devices may need specific update procedures; always backup configuration before applying firmware updates

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

Fix this in Insydeh2o Scoped from the published advisory
  • Consultation6.0 h
  • Implementation16.0 h
  • Testing12.0 h
  • Review / QA8.0 h
42.0 hours of engineering $7,320
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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-2021-41837 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
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