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CVE Record

CVE-2020-5953: A vulnerability exists in System Management Interrupt (SWSMI) handler of InsydeH2O UEFI Firmware code locat...

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).

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

This CVE concerns InsydeH2O UEFI firmware, the low-level code that starts and protects a device. The reported flaw could let an attacker who already has kernel-level control move into System Management Mode, a deeper firmware privilege layer. That can undermine normal operating-system security controls.

Executive priority

Treat this as a high-priority firmware exposure where affected assets are confirmed. The main business concern is persistence and control below the operating system, but urgency depends on vendor applicability and whether firmware updates exist for your fleet.

Technical view

The source describes an InsydeH2O SWSMI handler dereferencing the gRT EFI_RUNTIME_SERVICES pointer and calling GetVariable outside SMRAM. The stated impact is SMM code execution, escalating from ring 0 to ring -2. Public bundle data does not include CVSS, CWE, or precise affected versions.

Likely exposure

Exposure is most likely on systems whose OEM firmware includes affected InsydeH2O code. The bundle names Siemens and NetApp advisories, but does not provide product/version details in-line. Asset owners need vendor-specific firmware status checks.

Exploitation context

The bundle does not show CISA KEV listing or active exploitation evidence. The described path is privilege escalation from ring 0 to SMM, so it is not presented as remote initial access.

Researcher notes

Key evidence is limited to the CVE description and referenced advisories. The affected product list in the bundle is not populated. Do not infer additional vendors, exploit availability, or remediation beyond vendor guidance.

Mitigation direction

  • Review OEM, Siemens, NetApp, and Insyde advisories for affected firmware status.
  • Apply vendor-provided UEFI or BIOS firmware updates where available.
  • Prioritize assets where firmware trust affects regulated or critical operations.
  • Reduce kernel compromise paths through endpoint hardening and least privilege.
  • Track firmware update completion separately from operating-system patch status.

Validation and detection

  • Inventory devices using InsydeH2O UEFI firmware or referenced vendor platforms.
  • Compare installed BIOS or UEFI versions against vendor advisory guidance.
  • Confirm whether Siemens SSA-306654 applies to managed assets.
  • Confirm whether NetApp NTAP-20220222-0005 applies to managed assets.
  • Check vulnerability management records for firmware, not only OS packages.
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

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

description · low confidence lookup

Execution behavior lookup

The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.

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cve · low confidence lookup

CVE-2020-5953 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

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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.