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CVE Record

CVE-2021-33834: An issue was discovered in iscflashx64.sys 3.9.3.0 in Insyde H2OFFT 6.20.00.

An issue was discovered in iscflashx64.sys 3.9.3.0 in Insyde H2OFFT 6.20.00. When handling IOCTL 0x22229a, the input used to allocate a buffer and copy memory is mishandled. This could cause memory corruption or a system crash.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

This CVE concerns an Insyde firmware update driver that can mishandle input and corrupt memory. The documented impact is system instability or crash, not confirmed data theft or remote compromise. Business urgency depends on whether the affected H2OFFT package or driver is present in your endpoint or firmware-maintenance workflows.

Executive priority

Treat this as an exposure-discovery and vendor-follow-up item. Prioritize environments that run firmware update tools at scale or keep vendor utilities installed on endpoints. Urgency should rise if affected drivers are broadly deployed or tied to critical endpoint management workflows.

Technical view

iscflashx64.sys 3.9.3.0 in Insyde H2OFFT 6.20.00 mishandles input for IOCTL 0x22229a when allocating a buffer and copying memory. Sources describe memory corruption or system crash. No CVSS, CWE, CPE, exploitability details, or affected OEM product mapping are provided in the bundle.

Likely exposure

Exposure is most likely where Insyde H2OFFT 6.20.00 or iscflashx64.sys 3.9.3.0 is installed, bundled, or used for firmware update operations. The provided data does not identify specific OEM devices, CPEs, operating systems, or deployment prevalence.

Exploitation context

There is no KEV listing and no provided source claims active exploitation. The bundle describes a vulnerable IOCTL handling path but does not state required privileges, attack vector, exploit maturity, or whether code execution is possible.

Researcher notes

The public record is sparse. The core issue is unsafe IOCTL input handling leading to memory corruption or crash. Important missing details include privilege requirements, reachability, affected OEM mappings, fixed versions, and whether exploitation can exceed denial of service.

Mitigation direction

  • Check Insyde SA-2021004 and OEM advisories for supported updates or replacement packages.
  • Inventory systems for H2OFFT 6.20.00 and iscflashx64.sys 3.9.3.0.
  • Remove or restrict affected firmware update tooling where it is not operationally required.
  • Use vendor-approved firmware update packages from trusted distribution channels only.
  • Track crashes or driver faults involving iscflashx64.sys during firmware maintenance workflows.

Validation and detection

  • Confirm whether iscflashx64.sys version 3.9.3.0 exists on managed endpoints or images.
  • Check software deployment records for Insyde H2OFFT 6.20.00 packages.
  • Review vendor and OEM guidance before declaring a system remediated.
  • Verify updated tooling no longer includes the affected driver version.
  • Document any devices where vendor guidance is unavailable or ambiguous.
Prepared
Confidence
medium
Sources
4

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-2021-33834 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
3Source 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.