# CVE-2026-19023 — The HDF Group HDF5

> As of 2026-08-06, CVE-2026-19023 is a Medium-severity (band derived from the CVSS v4.0 score, not stated by the CNA) vulnerability in The HDF Group HDF5, CVSS v4.0 6.8, EPSS 0.1% (1.9th percentile). No Threadlinqs-tracked threat campaign has been attributed to CVE-2026-19023 as of 2026-08-06; the identifier is re-checked against the Threadlinqs threat corpus on every daily ingest.

**Last updated:** 2026-08-06

## What is CVE-2026-19023?

Untrusted pointer dereference in the render_bin_output function in the h5dump tool in HDF5 before 2.3.0 allows attackers to cause a denial of service via a variable-length string dataset with more than one element dumped in binary mode, which corrupts the per-element stride calculation and causes subsequent elements to be read from a misaligned offset and dereferenced as a pointer.

The record classifies CVE-2026-19023 under weakness class [CWE-822](https://intel.threadlinqs.com/cwe/CWE-822). 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 61 days ago.

## Severity and exploitation probability

- **CVSS v4.0 base score:** 6.8 — Medium (derived from score) (`CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N`)
- **EPSS (FIRST):** 0.1% probability of exploitation in the next 30 days, higher than 1.9% of all scored CVEs
- **CISA KEV:** Not listed in the CISA Known Exploited Vulnerabilities catalog
- **Threadlinqs priority:** 3.5/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- **Published:** 2026-08-05, last modified 2026-08-06

## Is CVE-2026-19023 being exploited?

It currently carries a trending score of 30 in the Threadlinqs vulnerability feed.

## Affected products and versions

- **The HDF Group**: HDF5

## How to fix CVE-2026-19023

No vendor patch reference has been recorded for CVE-2026-19023 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.

## Threat activity tracking CVE-2026-19023

No threat campaign in the Threadlinqs corpus currently references CVE-2026-19023, in its CVE list or as an indicator. The linkage is recomputed from the live corpus on every daily ingest, so this section fills in as soon as a tracked campaign cites the identifier.

## Sources

Enriched from CVE.org, FIRST EPSS, GitHub Security Advisories. Last verified by Threadlinqs on 2026-08-06.

**Other references**

- [github.com](https://github.com/HDFGroup/hdf5/issues/6486)

Canonical: https://intel.threadlinqs.com/cve/CVE-2026-19023
Full detection coverage and IOCs for threats exploiting CVE-2026-19023 via the Threadlinqs MCP server (Purple tier): https://intel.threadlinqs.com/mcp