CVE-2021-42059
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 · uneditedAn issue was discovered in Insyde InsydeH2O Kernel 5.0 before 05.08.41, Kernel 5.1 before 05.16.41, Kernel 5.2 before 05.26.41, Kernel 5.3 before 05.35.41, and Kernel 5.4 before 05.42.20. A stack-based buffer overflow leads toarbitrary code execution in UEFI DisplayTypeDxe DXE driver.
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 confidenceA stack-based buffer overflow vulnerability exists in the UEFI DisplayTypeDxe DXE driver of Insyde InsydeH2O kernel versions 5.0 through 5.4. The flaw allows arbitrary code execution due to improper bounds checking when handling display type data, potentially enabling an attacker to execute malicious code at the firmware level.
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>= 5.0, < 5.08.41>= 5.1, < 5.16.41>= 5.2, < 5.26.41>= 5.3, < 5.35.41>= 5.4, < 5.42.20all versionsall versionsall versionsall versionsall versionsall versionsall versionsCVSS 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
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/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 checksWork through these to decide whether this CVE applies to you.
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Identify the UEFI firmware vendorRun 'dmidecode -s bios-vendor' or check the BIOS/UEFI setup screen during boot to determine if the system uses Insyde InsydeH2O firmwareAffected if The firmware vendor is Insyde and the system is a PC or embedded device using InsydeH2O kernel
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Determine the InsydeH2O kernel versionRun 'dmidecode -s bios-version' or use a UEFI firmware extraction tool (like uefi-firmware-parser or chipsec) to read the firmware version from the ROM image. The version string typically appears in the BIOS version field (e.g., 5.x.x)Affected if A version is returned that matches the InsydeH2O version numbering scheme (5.0 through 5.4 family)
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Compare installed version against affected rangesCompare the identified version to these vulnerable 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, or 5.4 to <5.42.20Affected if The installed version falls within any of these ranges (e.g., 5.2.15 or 5.4.10)
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Identify Siemens Simatic device modelRun 'dmidecode -s system-product-name' or physically inspect the device label to identify the exact modelAffected if The model matches any of: Simatic Field Pg M5, Field Pg M6, Ipc127e, Ipc227g, Ipc277g, Ipc327g, or Ipc377g (all versions of these are affected regardless of InsydeH2O version)
You are affected if your system runs Insyde InsydeH2O kernel versions 5.0-5.4 within the vulnerable version ranges, or if your device is a Siemens Simatic Field Pg M5/M6 or Simatic Ipc127e/227g/277g/327g/377g (all versions).
Generated from the published advisory. Verify against your own configuration.
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 · scoped5.08.415.16.415.26.41
Apply the appropriate InsydeH2O kernel firmware update (05.08.41 or later for 5.0, 05.16.41 or later for 5.1, 05.26.41 or later for 5.2, 05.35.41 or later for 5.3, 05.42.20 or later for 5.4) from the system manufacturer. This is a firmware-level fix that cannot be addressed through software patches alone.
InsydeH2O Kernel 5.0 to >=05.08.41, Kernel 5.1 to >=05.16.41, Kernel 5.2 to >=05.26.41, or Kernel 5.3 to >=05.35.41; Siemens devices require vendor-specific firmware from Siemens
- 1. Identify the InsydeH2O kernel version currently installed on the affected system by checking the UEFI/BIOS firmware version or using tools like 'dmidecode' on Linux or 'wmic' on Windows
- 2. For InsydeH2O-based systems: Determine which kernel branch is in use (5.0, 5.1, 5.2, or 5.3)
- 3. Download and apply the appropriate fixed firmware version from Insyde or the OEM vendor: for kernel 5.0 upgrade to >=05.08.41, for kernel 5.1 upgrade to >=05.16.41, for kernel 5.2 upgrade to >=05.26.41, for kernel 5.3 upgrade to >=05.35.41
- 4. For Siemens Simatic devices (Field Pg M5/M6, Ipc127e, Ipc227g, Ipc277g, Ipc327g, Ipc377g): Contact Siemens for device-specific firmware updates that address this vulnerability
- 5. After applying firmware updates, verify the version has been correctly installed and confirm the vulnerability is resolved
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation3.0 h
- Implementation4.0 h
- Testing2.0 h
- Review / QA2.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2021-42059 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2021-42059 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
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