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Insydeh2oApplication · Insyde

CVE-2020-5953

HIGH · 7.5 CVSS v3.1 Published 2022-02-03
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
77/100
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
A vulnerability exists in System Management Interrupt (SWSMI) handler of InsydeH2O UEFI Firmware code located in SWSMI handler that dereferences gRT (EFI_RUNTIME_SERVICES) pointer to call a GetVariable service, which is located outside of SMRAM. This can result in code execution in SMM (escalating privilege from ring 0 to ring -2).

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

InsydeH2O UEFI firmware contains a SMM callout vulnerability in its SWSMI handler. The handler improperly dereferences the gRT (EFI_RUNTIME_SERVICES) pointer to call GetVariable services located outside the protected SMRAM, allowing a local attacker with ring 0 privileges to execute code in System Management Mode (ring -2).

MitigationApply the vendor-supplied UEFI firmware update from Insyde or the OEM that addresses this SMM callout vulnerability; this typically requires coordinating with hardware vendors and updating firmware on affected systems.

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:= 5.12.09.0074= 5.23.04.0045= 5.23.45.0023= 5.33.15.0034= 5.34.03.0029= 5.42.03.0010
Ruggedcom Ape1808 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 Itp1000 FirmwareOperating system
Affected:all versions
Simatic Ipc477e Pro 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
High
Privileges
High
User interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:H/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 UEFI firmware vendor and version
    Run 'dmidecode -s bios-version' or check UEFI/BIOS setup screen for version information. For InsydeH2O, look for version strings like 5.12.x, 5.23.x, 5.33.x, or 5.34.x
    Affected if The firmware version matches one of the affected InsydeH2O versions: 5.12.09.0074, 5.23.04.0045, 5.23.45.0023, 5.33.15.0034, 5.34.03.0029, or 5.42.03.0010
  2. Identify system hardware model
    Run 'dmidecode -s system-product-name' or 'dmidecode -s system-manufacturer' to identify the device model and vendor
    Affected if The system is a Siemens Ruggedcom Ape1808, Simatic Field Pg M6, Simatic Ipc127e, Simatic Ipc227g, Simatic Ipc277g, Simatic Itp1000, or Simatic Ipc477e Pro (all versions are affected)
  3. Confirm InsydeH2O firmware in use
    Check UEFI firmware vendor information via 'dmidecode -s bios-vendor' or by inspecting the UEFI setup screen
    Affected if The BIOS vendor is Insyde or the firmware identifies as InsydeH2O and the version matches affected ranges
  4. Verify local privileged access context
    Confirm the system is running a full OS where an attacker could obtain ring 0 (kernel/root) privileges; this is not exploitable remotely
    Affected if The system runs a general-purpose OS with multi-user access where local attackers could obtain kernel-level privileges

Your system is affected if it uses InsydeH2O firmware matching one of the six specific versions listed OR is any Siemens device model from the eight listed families, and an attacker with local kernel privileges could potentially exploit the SMM callout vulnerability.

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.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply the vendor-supplied UEFI firmware update from Insyde or the OEM that addresses this SMM callout vulnerability; this typically requires coordinating with hardware vendors and updating firmware on affected systems.

Fix this in Insydeh2o Scoped from the published advisory
  • Consultation8.0 h
  • Implementation16.0 h
  • Testing12.0 h
  • Review / QA8.0 h
44.0 hours of engineering $7,720
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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-2020-5953 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