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NVD / CVE Program· CNA GitHub_M

CVE-2026-26197: Array full size, element count, and element size are not checked to make sure they match in H5Odtype.c

MediumCVSS 5.9 · v4.0—No exploit Fix available

Noroxi assessment

Priority: Monitor (action score 23/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.36% (FIRST EPSS).
  • Anyone who can reach it over the internet can trigger it. No account or password is required. Special conditions such as timing or configuration are required.
  • Fixed version: azl3 hdf5 1.14.6-4 on Azure Linux 3.0 1.14.6-4.

Low priority for now. Upgrade to azl3 hdf5 1.14.6-4 on Azure Linux 3.0 1.14.6-4 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

HDF5 is a high-performance library and a file format specification that implements the HDF5 data model. If a file is corrupted such that an array datatype's size, the number of elements, and the element size are not in agreement it can trigger an out of bounds read. The array datatype stores the full size of the datatype (`dt->shared->size`) separately from the number of elements (`dt->shared->u.array.nelem`) and the element size (`dt->shared->parent->shared->size`). If any one of these are corrupted so that they don't align with the others (element size * nelem = full size), it can lead to an out of bounds read. Depending on what is corrupted, it can alter the type of out of bounds read triggered. The vulnerability is present only in files that have been maliciously altered, as its generally not possible to independently alter the full size of the datatype, the element count and the element size. As such, this is only present if a malicious actor is altering files, and won't appear in regular usage.

Published
Jul 20, 2026
Updated
Oct 24, 2026
EPSS
0.3% · 30th percentile

Report tools

JSON

Action score

23

Monitor

Low priority for now.

CVSS
23 / 40 · 5.9 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.3%

CISA SSVC decision

Exploitation
proof of concept
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · GitHub_M
5.9
NVD has not scored this yet; the score shown is the CNA’s.

CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2026-26197

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
hdfgrouphdf5

Versions reported by the vendor

Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.

  • HDFGroup hdf5

    • < 2.0.0affected

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • hdfgroup hdf5before 2.1.0

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12hdf5from 0—
Debian:14hdf5before 2.1.0+repack-12.1.0+repack-1
Red Hat:hummingbird:1hdf5before 0:2.2.0-0.1.1.hum10:2.2.0-0.1.1.hum1
Red Hat:hummingbird:1hdf5-develbefore 0:2.2.0-0.1.1.hum10:2.2.0-0.1.1.hum1
Red Hat:hummingbird:1hdf5-mpichbefore 0:2.2.0-0.1.1.hum10:2.2.0-0.1.1.hum1
Red Hat:hummingbird:1hdf5-mpich-develbefore 0:2.2.0-0.1.1.hum10:2.2.0-0.1.1.hum1
Red Hat:hummingbird:1hdf5-mpich-staticbefore 0:2.2.0-0.1.1.hum10:2.2.0-0.1.1.hum1
Red Hat:hummingbird:1hdf5-openmpibefore 0:2.2.0-0.1.1.hum10:2.2.0-0.1.1.hum1
Red Hat:hummingbird:1hdf5-openmpi-develbefore 0:2.2.0-0.1.1.hum10:2.2.0-0.1.1.hum1
Red Hat:hummingbird:1hdf5-openmpi-staticbefore 0:2.2.0-0.1.1.hum10:2.2.0-0.1.1.hum1
Red Hat:hummingbird:1hdf5-staticbefore 0:2.2.0-0.1.1.hum10:2.2.0-0.1.1.hum1
Red Hat:hummingbird:1java-hdf5before 0:2.2.0-0.1.1.hum10:2.2.0-0.1.1.hum1

Same product

hdfgroup: all records

Other highest-scoring records for the same primary product.

  • CVE-2018-13876An issue was discovered in the HDF HDF5 1.8.20 library.
    40Plan
  • CVE-2018-13874An issue was discovered in the HDF HDF5 1.8.20 library.
    40Plan
  • CVE-2018-13873An issue was discovered in the HDF HDF5 1.8.20 library.
    40Plan

Published before and after this one in the same product

  • ← EarlierCVE-2026-34734Apr 9, 2026 · HDF5: H5T__conv_struct Use After Free
    31Monitor
  • ← EarlierCVE-2026-29043Apr 10, 2026 · HDF5 H5T__ref_mem_setnull Heap Buffer Overflow
    22Monitor
  • Later →CVE-2026-26199Jul 20, 2026 · Buffer underflow in `H5Iget_name `/`H5G_get_name` if size is zero
    23Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
azl3 hdf5 1.14.6-4 on Azure Linux 3.01.14.6-4 · CBL-Mariner ReleasesMicrosoft (MSRC)
debian:hdf52.1.0+repack-1 · Debian:14Package registry (OSV)
red hat:hdf50:2.2.0-0.1.1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:hdf5-devel0:2.2.0-0.1.1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:hdf5-mpich0:2.2.0-0.1.1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:hdf5-mpich-devel0:2.2.0-0.1.1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:hdf5-mpich-static0:2.2.0-0.1.1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:hdf5-openmpi0:2.2.0-0.1.1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:hdf5-openmpi-devel0:2.2.0-0.1.1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:hdf5-openmpi-static0:2.2.0-0.1.1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:hdf5-static0:2.2.0-0.1.1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:java-hdf50:2.2.0-0.1.1.hum1 · Red Hat:hummingbird:1Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2026-120757106 days apartHeap Buffer Over-read via Non-Terminated Link Data in H5L__extern_traverse
    27Monitor
  • CVE-2026-175727 days apartHDF5 SOHM List Index Heap Buffer Overflow
    22Monitor
  • CVE-2026-120755106 days apartInteger Underflow Leads to Out-of-Bounds Read via Truncated Chunk in HDF5 Szip Filter
    18Monitor
  • CVE-2026-120756106 days apartHeap Buffer Over-read via Malformed Message Size in HDF5's H5O__chunk_deserialize
    7Monitor

Not on record for this CVE: patch commit or PR link · researcher credit · public bounty program.

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • Special conditions such as timing or configuration are required.

If successful

Confidentiality
Integrity
Availability
Attack vector
Network
Attack complexity
High
Privileges required
None
User interaction
A
Scope
X

Weakness class (CWE)

CWE-125 · Out-of-bounds Read

CVSS vector

CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

—

All records