# CVE-2026-19025: HDF5 divide-by-zero (SIGFPE) via mismatched chunk-layout dimensionality and dataspace rank on dataset open

> Attackers can cause a denial of service via divide-by-zero crash in HDF5 library by opening crafted files with mismatched chunk and dataspace ranks.

- **Severity:** Medium 6.8 (`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`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 5 Aug 2026
- **Updated:** 6 Aug 2026
- **Also known as:** AZL-94490, DEBIAN-CVE-2026-19025, ECHO-5e92-f075-6b1a, GHSA-546v-jw2p-gc8p, UBUNTU-CVE-2026-19025

## What is CVE-2026-19025?

CVE-2026-19025 is a medium-severity denial of service vulnerability in The HDF Group HDF5, published on 5 Aug 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

### Official description

H5O__layout_decode in H5Olayout.c in HDF5 through 2.3.0 does not validate that a chunked dataset's stored chunk-layout dimensionality matches its dataspace rank when an existing dataset is opened, whereas this check is performed only at dataset-creation time. This allows attackers to cause a denial of service (divide-by-zero and application crash in H5S__hyper_iter_get_seq_list in src/H5Shyper.c) via a crafted HDF5 file with mismatched chunk/dataspace ranks that is opened and read via H5Dopen2 and H5Dread, e.g. by the h5repack tool.

Weakness: CWE-369 (Divide By Zero)

## Which versions are affected by CVE-2026-19025?


## How do I fix CVE-2026-19025?

Apply the vendor's patch.

## Is CVE-2026-19025 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-19025 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-19025 and fix it if it is affected.

What it is: CVE-2026-19025 is a medium-severity denial of service vulnerability in The HDF Group HDF5, published on 5 Aug 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-19025 exists.

Affected product: The HDF Group HDF5. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-19025/ (Markdown: https://insights.sbomify.com/CVE-2026-19025/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-19025
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-19025
- OSV: https://osv.dev/vulnerability/CVE-2026-19025

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-19025/
Summaries are generated and may contain mistakes; the official description above is the record.