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Insydeh2oApplication · Insyde

CVE-2021-41840

HIGH · 8.2 CVSS v3.1 Published 2022-02-03
Fix available
A fix is available. Upgrade to 5.23.35 / 5.32.35 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 NvmExpressDxe in the kernel 5.0 through 5.5 in Insyde InsydeH2O. There is an SMM callout that allows an attacker to access the System Management Mode and execute arbitrary code. This occurs because of Inclusion of Functionality from an Untrusted Control Sphere.

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

NvmExpressDxe driver in InsydeH2O UEFI firmware (kernels 5.0-5.5) contains an SMM callout vulnerability allowing an attacker to access System Management Mode and execute arbitrary code due to inclusion of functionality from an untrusted control sphere.

MitigationApply vendor-supplied firmware update for InsydeH2O to patch the vulnerable NvmExpressDxe driver; if unavailable, implement SMM lockdown or memory protection measures.

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:>= 5.2, < 5.23.35>= 5.3, < 5.32.35>= 5.4, < 5.40.35

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 installed InsydeH2O firmware version
    Access the UEFI/BIOS setup screen or use system information tools (like dmidecode on Linux or msinfo32 on Windows) to retrieve the BIOS version and vendor information
    Affected if The firmware version matches InsydeH2O kernel 5.0-5.5 and falls within the affected version ranges (>=5.2/<5.23.35, >=5.3/<5.32.35, or >=5.4/<5.40.35)
  2. Confirm the NvmExpressDxe driver is present
    Check the UEFI firmware image or running UEFI environment for the NvmExpressDxe driver module - this can be done via UEFI shell, firmware extraction tools, or system firmware logs
    Affected if The NvmExpressDxe driver is loaded or present in the firmware image
  3. Verify SMM configuration state
    Examine SMM configuration settings in UEFI/BIOS setup or query SMM status via system management tools - look for SMM protection or lockdown features
    Affected if SMM protection measures are not enabled or are bypassed, leaving the SMM attack surface exposed

A system is affected if it runs InsydeH2O firmware with kernel versions 5.2-5.23.34, 5.3-5.32.34, or 5.4-5.40.34, contains the vulnerable NvmExpressDxe driver, and does not have SMM protection enabled.

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 5.23.35 / 5.32.35 / 5.40.35 or later
Fixed in 5.23.355.32.355.40.35
Interim mitigation

Apply vendor-supplied firmware update for InsydeH2O to patch the vulnerable NvmExpressDxe driver; if unavailable, implement SMM lockdown or memory protection measures.

Recommended fix High confidence

InsydeH2O >= 5.40.35 (or the minimum fixed version for your branch: 5.23.35 for 5.2.x, 5.32.35 for 5.3.x)

  1. 1. Identify the InsydeH2O firmware version currently installed on the affected system via UEFI setup or system information tools
  2. 2. Determine the applicable firmware branch based on the current version (5.2.x, 5.3.x, or 5.4.x)
  3. 3. Obtain the patched firmware update from the system manufacturer (OEM) or Insyde (if available directly)
  4. 4. Apply the firmware update following the OEM's standard UEFI firmware update process, typically via firmware update utility or through UEFI setup menu
  5. 5. Verify the firmware version has been updated to 5.23.35 or higher (for 5.2 branch), 5.32.35 or higher (for 5.3 branch), or 5.40.35 or higher (for 5.4 branch)
Caveat Firmware updates carry risk of bricking the system if interrupted; ensure stable power and follow OEM update procedures precisely

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
  • Testing4.0 h
  • Review / QA2.0 h
18.0 hours of engineering $3,200
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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-2021-41840 in production — separate from our analysis above.

No notes yet

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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
  • No spam, self-promotion, credentials, or personal data