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Insydeh2oApplication · Insyde

CVE-2021-41839

HIGH · 8.2 CVSS v3.1 Published 2022-02-03
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 NvmExpressDxe 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

Untrusted pointer dereference in NvmExpressDxe driver in InsydeH2O BIOS (kernel 5.0-5.5) allows an attacker to corrupt SMM memory and write predictable data to SMRAM, leading to SMM privilege escalation.

MitigationApply vendor-supplied BIOS/firmware updates from Insyde or original equipment manufacturers; disable SMM write protection vulnerabilities via firmware configuration if available.

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, < 5.51.25

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 BIOS vendor
    Run 'dmidecode -s bios-vendor' or check system information to determine if the BIOS is InsydeH2O
    Affected if The BIOS vendor is not InsydeH2O, the system is not affected by this specific CVE
  2. Check the InsydeH2O kernel version
    Run 'dmidecode -s bios-version' to retrieve the BIOS firmware version string, which contains the InsydeH2O kernel version (e.g., 5.0, 5.3, 5.4, 5.5)
    Affected if The kernel version falls within 5.0-5.5 and the full version is less than the patched versions (5.16.25, 5.26.25, 5.35.25, 5.43.25, or 5.51.25 depending on the kernel branch)
  3. Verify NVMe storage controller is present
    Run 'lspci | grep -i nvme' or check if /sys/block/nvme* exists to determine if an NVMe storage device is installed
    Affected if No NVMe device is present, the NvmExpressDxe driver may not be loaded, reducing exploitation surface
  4. Check if SMM is accessible
    Inspect system firmware settings or run 'dmesg | grep -i smm' to check System Management Mode configuration status
    Affected if SMM write protection is disabled or not properly configured, the vulnerability could potentially be exploited

The system is affected if it uses InsydeH2O BIOS with kernel version 5.0-5.5 where the full version falls below the patched thresholds (5.16.25, 5.26.25, 5.35.25, 5.43.25, or 5.51.25), and has an active NVMe storage controller that loads the vulnerable NvmExpressDxe driver.

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

Apply vendor-supplied BIOS/firmware updates from Insyde or original equipment manufacturers; disable SMM write protection vulnerabilities via firmware configuration if available.

Recommended fix High confidence

InsydeH2O firmware version 5.16.25, 5.26.25, 5.35.25, or 5.43.25 (depending on current branch)

  1. Identify the current InsydeH2O firmware version running on the system (typically displayed during POST or available in BIOS setup under 'BIOS Version' or 'UEFI Version')
  2. Determine which version branch the current firmware is on (5.1.x, 5.2.x, 5.3.x, or 5.4.x)
  3. Navigate to Insyde's official support portal at www.insyde.com to obtain the fixed firmware version
  4. Download the appropriate fixed firmware version: 5.16.25 (for 5.1.x branch), 5.26.25 (for 5.2.x branch), 5.35.25 (for 5.3.x branch), or 5.43.25 (for 5.4.x branch)
  5. Apply the firmware update using the vendor's recommended method - typically through a BIOS update utility, Insyde's firmware update tool, or through the UEFI firmware flash utility
  6. Reboot the system to complete the update process and verify the new firmware version is installed

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

Fix this in Insydeh2o Scoped from the published advisory
  • Consultation8.0 h
  • Testing4.0 h
  • Review / QA2.0 h
14.0 hours of engineering $2,560
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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-2021-41839 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