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CVE Record

CVE-2026-26200: HDF5 Affected by H5T__conv_struct_opt Heap Buffer Overflow

HDF5 is software for managing data. Prior to version 1.14.4-2, an attacker who can control an `h5` file parsed by HDF5 can trigger a write-based heap buffer overflow condition. This can lead to a denial-of-service condition, and potentially further issues such as remote code execution depending on the practical exploitability of the heap overflow against modern operating systems. Real-world exploitability of this issue in terms of remote-code execution is currently unknown. Version 1.14.4-2 fixes the issue.

HighCVSS 7.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

HDF5 versions before 1.14.4-2 can mishandle a crafted h5 file and overwrite heap memory. The most supported business impact is application crash or service disruption. Remote code execution is described as possible but not confirmed in the provided sources.

Executive priority

Treat as high priority for environments processing external scientific, analytics, or model data files. Patch exposed parsing workflows first, but avoid assuming active exploitation or confirmed remote-code-execution impact from the current evidence.

Technical view

CVE-2026-26200 is a write-based heap buffer overflow in HDF5 H5T__conv_struct_opt, associated with CWE-122 and CWE-131. The CVSS 3.1 score is 7.8 with local attack vector and required user interaction. HDF5 1.14.4-2 fixes the issue.

Likely exposure

Exposure is most likely where applications, research tools, data pipelines, or desktop software parse user-supplied or externally sourced h5 files using HDF5 versions before 1.14.4-2.

Exploitation context

The source bundle does not show CISA KEV listing or active exploitation evidence. Attack requires an attacker-controlled h5 file to be parsed by vulnerable HDF5. Practical remote-code-execution exploitability is explicitly unknown.

Researcher notes

Key uncertainty is exploitability beyond denial of service on modern platforms. Focus validation on vulnerable library reachability, untrusted file ingestion paths, packaging backports, and whether vulnerable conversion code is reachable in product workflows.

Mitigation direction

  • Upgrade HDF5 to version 1.14.4-2 or later where feasible.
  • Check operating system and package vendor guidance for backported fixes.
  • Limit processing of untrusted h5 files until affected systems are patched.
  • Prioritize systems that parse external files automatically or at scale.

Validation and detection

  • Inventory HDF5 versions in applications, containers, workstations, and data pipelines.
  • Confirm whether any deployed version is earlier than 1.14.4-2.
  • Identify workflows that parse externally supplied h5 files.
  • Review vendor advisories for fixed package names and distro-specific status.
Prepared
Confidence
medium
Sources
6

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.

cwe · low confidence lookup

CWE-122: Exact CWE lookup

Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

Open ATT&CK lookup
cwe · low confidence lookup

CWE-131: Exact CWE lookup

Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

Open ATT&CK lookup
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.

Open ATT&CK lookup
cve · low confidence lookup

CVE-2026-26200 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
High
CVSS
7.8 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

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.

2CVSS vectors
5Timeline events
2ADP providers
5Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: noTechnical Impact: total

CVSS vector scores

2 official scores

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
7.8CVSS 3.1HighCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H1.85.9GitHub_M
7.8CVSS 3.1HighCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H1.85.9redhat-SADP

Vulnerability scoring details

Base CVSS 3.1 score

7.8High
CVSS 3.1 vector shape for CVE-2026-26200Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. ADP timelineredhat-SADP

    Made public.

  3. CVE publishedCVE Program

    The CVE record was published.

  4. ADP timelineredhat-SADP

    Reported to Red Hat.

  5. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
other:ssvc
redhat-SADPhdf5: HDF5: Denial of Service due to heap buffer overflow when parsing a crafted h5 file
other:Red Hat severity ratingcvssV3_1
  • 2026-02-19T20:05:33.115Z: Reported to Red Hat.
  • 2026-02-19T19:19:10.512Z: Made public.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
HDFGrouphdf5< 1.14.4-2Listed
Weakness

CWE details

CWE-122CWE-131

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