How severe is CVE-2026-26199?

CVE-2026-26199 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability low.

Is CVE-2026-26199 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (17th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-26199?

CVE-2026-26199 affects Hdfgroup Hdf5. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-26199?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2026-26199 published?

CVE-2026-26199 was published on 2026-07-20 and last updated on 2026-07-29.

CVE-2026-26199

CVE-2026-26199 is a medium-severity vulnerability in Hdfgroup Hdf5 with a CVSS 3.x base score of 6.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-124.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
CVSS v4: 5.9
EPSS exploit prediction: 0% (17th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-124
Affected product: Hdfgroup Hdf5
Published: 2026-07-20
Last modified: 2026-07-29

Description

HDF5 is a high-performance library and a file format specification that implements the HDF5 data model. If `H5Iget_name` is invoked on a group id with `0` for the size parameter, it will underflow when trying to place a null terminator in the buffer. This can occur if `H5Iget_name` is invoked in a way where `size` can be forced to zero, and there is important data before the `name` buffer.

Frequently asked questions

What is CVE-2026-26199?: HDF5 is a high-performance library and a file format specification that implements the HDF5 data model. If `H5Iget_name` is invoked on a group id with `0` for the size parameter, it will underflow when trying to place a null terminator in the buffer. This can occur if `H5Iget_name` is invoked in a way where `size` can be forced to zero, and there is important data before the `name` buffer.
How severe is CVE-2026-26199?: CVE-2026-26199 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability low.
Is CVE-2026-26199 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (17th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-26199?: CVE-2026-26199 affects Hdfgroup Hdf5. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-26199?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2026-26199 published?: CVE-2026-26199 was published on 2026-07-20 and last updated on 2026-07-29.

References

Affected products (1)

cpe:2.3:a:hdfgroup:hdf5:*:*:*:*:*:*:*:*

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