CVE-2026-26197Network attack vector

Application crash via inconsistent array datatype metadata

Published Jul 20, 2026 · Updated Jul 20, 2026

Out-of-bounds reads in HDF5 before 2.0.0 allow remote attackers to crash applications that process a maliciously altered file. H5Odtype.c stores the total array datatype size, element count, and parent element size separately without verifying that total size equals count multiplied by element size. Exploitation requires an application or bundled tool such as h5dump or h5repack to parse a deliberately corrupted HDF5 file; the demonstrated consequence is a crash or stack corruption, not data disclosure.

CVSS severity5.9
Medium
EPSS probability0.32%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Out-of-bounds reads in HDF5 before 2.0.0 allow remote attackers to crash applications that process a maliciously altered file. H5Odtype.c stores the total array datatype size, element count, and parent element size separately without verifying that total size equals count multiplied by element size. Exploitation requires an application or bundled tool such as h5dump or h5repack to parse a deliberately corrupted HDF5 file; the demonstrated consequence is a crash or stack corruption, not data disclosure.

The record

CVE
CVE-2026-26197
Published
Jul 20, 2026
Updated
Jul 20, 2026
Vendor
The HDF Group
Product
HDF5
Classifications
CWE-125, T1204.002
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 20, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 20, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 2.0.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The HDF Group · HDF5version=< 2.0.0

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
5.9GitHub, Inc.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

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-125Out-of-bounds Read
T1204.002Malicious File

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo