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CVE Record

CVE-2021-42554: An issue was discovered in Insyde InsydeH2O with Kernel 5.0 before 05.08.42, Kernel 5.1 before 05.16.42, Ke...

An issue was discovered in Insyde InsydeH2O with Kernel 5.0 before 05.08.42, Kernel 5.1 before 05.16.42, Kernel 5.2 before 05.26.42, Kernel 5.3 before 05.35.42, Kernel 5.4 before 05.42.51, and Kernel 5.5 before 05.50.51. An SMM memory corruption vulnerability in FvbServicesRuntimeDxe allows a possible attacker to write fixed or predictable data to SMRAM. Exploiting this issue could lead to escalating privileges to SMM.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

This is a firmware-level weakness in InsydeH2O. If exploited, an attacker could potentially gain highly privileged System Management Mode control, below the operating system. The bundle names fixed Insyde kernel versions, but does not provide CVSS scoring or confirmed exploitation.

Executive priority

Prioritize this for assets with confirmed affected firmware, especially servers, appliances, and operational technology. The risk is below the operating system, so normal endpoint controls may not detect compromise. Urgency should be driven by vendor confirmation and asset criticality.

Technical view

CVE-2021-42554 is an SMM memory corruption issue in FvbServicesRuntimeDxe. The CVE states an attacker may write fixed or predictable data to SMRAM, potentially escalating privileges to SMM. Affected InsydeH2O Kernel 5.0 through 5.5 releases are listed before specific fixed builds.

Likely exposure

Exposure depends on devices or appliances shipping affected InsydeH2O firmware. The bundle references Insyde, CERT/CC, NetApp, and Siemens advisories, but does not provide a complete product inventory. Asset-level confirmation requires OEM firmware advisories and fleet firmware data.

Exploitation context

The source bundle does not show KEV listing or confirmed active exploitation. The impact is serious because SMM compromise can bypass operating-system controls. The provided evidence does not describe prerequisites, exploit maturity, or weaponized public exploitation.

Researcher notes

The bundle lacks CVSS, CWE, exploit prerequisites, and complete affected-product mapping. Analysis should stay tied to firmware lineage and OEM advisories. Do not assume every InsydeH2O device is affected without kernel branch and build evidence.

Mitigation direction

  • Identify systems using affected InsydeH2O Kernel 5.0 through 5.5 firmware lines.
  • Obtain BIOS or firmware updates from the device OEM or affected vendor advisory.
  • Update to OEM firmware containing the listed Insyde fixed kernel builds or later.
  • Review Insyde SA-2022012, CERT/CC, NetApp, and Siemens guidance for product-specific actions.
  • Escalate unsupported affected firmware to the vendor or plan replacement.

Validation and detection

  • Inventory UEFI/BIOS vendor, firmware version, and device model across managed assets.
  • Map models against OEM, Insyde, CERT/CC, NetApp, and Siemens advisories.
  • Confirm installed firmware is not below the fixed Insyde kernel build listed for its branch.
  • Record exceptions where firmware branch or OEM exposure cannot be determined.
  • Recheck vendor advisories after firmware updates for revised affected-product information.
Prepared
Confidence
medium
Sources
7

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

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CVE-2021-42554 mapping review

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
0Timeline events
0ADP providers
6Source links

CVSS and timeline data

No CVSS vectors or timeline events were available in the normalized CVE source material.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
n/an/an/aListed
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.