CVE-2026-26197: 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 ele

unknownCVE-2026-26197

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.

Details

Source: NVD Recent CVEs (US · database · site)
Severity: unknown
Published: 2026-07-20
Last updated: 2026-07-23
Exploitation: Not in CISA KEV at last sync

Original advisory: https://nvd.nist.gov/vuln/detail/CVE-2026-26197

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Low exploitation riskCVE-2026-261970.27% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 19% of all scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-26197	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.

unknownCVE-2026-26197: Array full size, element count, and element size are not checked to make sure they match in H5…msrc

Recent advisories for HDF5 is a

A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.

mediumCVE-2026-9335: A vulnerability in keras-team/keras versions <= 3.14.0 allows arbitrary local HDF5 file content…nvd · 2026-08-02
unknownCVE-2026-17574: HDF5 contains a NULL pointer dereference vulnerability. Processing a crafted HDF5 file contain…nvd · 2026-07-27
unknownCVE-2026-17573: A double free vulnerability was discovered in the HDF5 library. Processing a crafted HDF5 file…nvd · 2026-07-27
unknownCVE-2026-17572: Heap-based buffer overflow in the SOHM list-index deserialization code in HDF5 through 2.1.1 o…nvd · 2026-07-27
unknownCVE-2026-26199: HDF5 is a high-performance library and a file format specification that implements the HDF5 da…nvd · 2026-07-20
mediumCVE-2026-12480: Arbitrary HDF5 File Read via Virtual Dataset Bypass in keras-team/kerasmsrc · 2026-07-14