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Insydeh2oApplication · Insyde

CVE-2021-45970

HIGH · 8.2 CVSS v3.1 Published 2022-01-05
Fix available
A fix is available. Upgrade to 5.16.25 / 5.26.25 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 IdeBusDxe in Insyde InsydeH2O with kernel 5.1 before 05.16.25, 5.2 before 05.26.25, 5.3 before 05.35.25, 5.4 before 05.43.25, and 5.5 before 05.51.25. A vulnerability exists in the SMM (System Management Mode) branch that registers a SWSMI handler that does not sufficiently check or validate the allocated buffer pointer (the status code saved at the CommBuffer+4 location).

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

This is an SMM (System Management Mode) privilege escalation vulnerability in InsydeH2O's IdeBusDxe driver. A SWSMI handler in the SMM branch fails to properly validate a buffer pointer stored at CommBuffer+4 location, potentially allowing an attacker with user-mode or OS-level access to manipulate memory and execute code in the highly privileged SMM context.

MitigationUpdate InsydeH2O firmware to the patched versions: 05.16.25 or later for kernel 5.1, 05.26.25 or later for 5.2, 05.35.25 or later for 5.3, 05.43.25 or later for 5.4, and 05.51.25 or later for 5.5.

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:>= 5.1, < 5.16.25>= 5.2, < 5.26.25>= 5.3, < 5.35.25>= 5.4, < 5.43.25>= 5.5, < 05.51.25

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 firmware vendor
    Check system BIOS information via `dmidecode -s bios-vendor` or inspect the UEFI/BIOS setup screen for the firmware provider name
    Affected if The vendor is not Insyde (the vulnerability only affects InsydeH2O firmware)
  2. Determine the InsydeH2O kernel version
    Run `dmidecode -s bios-version` to retrieve the firmware version string; InsydeH2O versions typically follow patterns like 5.x.xx or 05.xx.25
    Affected if The version string cannot be retrieved or does not match InsydeH2O version format
  3. Compare firmware version against affected ranges
    Parse the version from step 2 and compare against: 5.1 to <5.16.25, 5.2 to <5.26.25, 5.3 to <5.35.25, 5.4 to <5.43.25, or 5.5 to <05.51.25
    Affected if The installed version falls within any of these vulnerable ranges
  4. Verify IdeBusDxe driver presence in SMM
    This requires UEFI firmware analysis tools (e.g., chipsec, uefi-firmware-parser) or contacting Insyde to confirm if the IdeBusDxe driver with the vulnerable SWSMI handler is present in the SMM configuration
    Affected if The IdeBusDxe driver with the vulnerable SMM handler code is present in the system firmware

A system is affected if it runs InsydeH2O firmware with a kernel version within the affected ranges AND contains the IdeBusDxe driver with the vulnerable SWSMI handler in SMM.

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 5.16.25 / 5.26.25 / 5.35.25 or later
Fixed in 5.16.255.26.255.35.25
Interim mitigation

Update InsydeH2O firmware to the patched versions: 05.16.25 or later for kernel 5.1, 05.26.25 or later for 5.2, 05.35.25 or later for 5.3, 05.43.25 or later for 5.4, and 05.51.25 or later for 5.5.

Recommended fix High confidence

InsydeH2O kernel 5.1 to >=05.16.25, kernel 5.2 to >=05.26.25, kernel 5.3 to >=05.35.25, kernel 5.4 to >=05.43.25, or kernel 5.5 to >=05.51.25

  1. Identify the current InsydeH2O kernel version by checking the UEFI/BIOS firmware version information on the affected system
  2. Navigate to the official Insyde support portal at www.insyde.com and locate the firmware downloads section
  3. Download the InsydeH2O firmware update corresponding to the kernel version branch (5.1, 5.2, 5.3, 5.4, or 5.5) that meets or exceeds the fixed release: 05.16.25, 05.26.25, 05.35.25, 05.43.25, or 05.51.25 respectively
  4. Apply the firmware update by following Insyde's standard UEFI firmware flashing procedure (typically via BIOS setup, firmware update utility, or vendor-specific tool)
  5. Verify the installed firmware version reflects the patched release after updating
Caveat Firmware updates carry inherent risk of bricking the system if interrupted; ensure stable power and follow vendor flashing instructions 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
  • Testing8.0 h
  • Review / QA4.0 h
24.0 hours of engineering $4,160
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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-2021-45970 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
  • No spam, self-promotion, credentials, or personal data