Is CVE-2026-26197 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-26197 being exploited in the wild.

How severe is CVE-2026-26197?

Informational severity, with a CVSS score of 5.9, published 20 July 2026.

Is there a fix for CVE-2026-26197?

No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

How is CVE-2026-26197 attacked?

It is attacked over the network or with local access, in a software library.

Am I affected by CVE-2026-26197?

Check whether anything you run is named in the advisory. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-26197: HDFGroup HDF5 out-of-bounds read in H5Odtype.c

CVE-2026-26197 · Severity: info · CVSS 5.9 · Published 2026-07-20

HDF5 is a high-performance library used for managing and storing large amounts of complex data. A vulnerability exists where a specially crafted, malicious HDF5 file can cause the library to crash or read unintended memory locations when the file is opened. This could lead to service disruptions or application instability if a user is tricked into processing a corrupted file.

Quick answers

Is CVE-2026-26197 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-26197 being exploited in the wild.
How severe is CVE-2026-26197?: Informational severity, with a CVSS score of 5.9, published 20 July 2026.
Which products and versions are affected?: HDFGroup hdf5 < 2.1.0.
Is there a fix for CVE-2026-26197?: No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2026-26197 attacked?: It is attacked over the network or with local access, in a software library.
Am I affected by CVE-2026-26197?: Check whether anything you run is named in the advisory. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

An out-of-bounds read vulnerability exists in HDF5 due to a lack of consistency checks between an array datatype's total size, number of elements, and individual element size in H5Odtype.c. Specifically, the library fails to verify that (element size * number of elements) equals the stored full size of the datatype. An attacker can exploit this by providing a maliciously altered HDF5 file with mismatched metadata, triggering out-of-bounds reads in various components such as H5Aint.c, H5Tconv_compound.c, and H5Dselect.c. This can result in application crashes or stack corruption. The issue is addressed in version 2.1.0.

Affected products

HDFGroup hdf5 < 2.1.0

Timeline

2026-06-26: advisory: GitHub advisory published by maintainer
2026-07-20: disclosed: NVD publication date

References

https://github.com/HDFGroup/hdf5/security/advisories/GHSA-gh44-7wpq-622f

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