# CVE-2026-26200: HDF5 Affected by H5T__conv_struct_opt Heap Buffer Overflow

> An attacker can trigger a heap buffer overflow in HDF5 by providing a malicious h5 file, causing denial of service or potential code execution.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H`)
- **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:** 19 Feb 2026
- **Updated:** 15 Jul 2026
- **Also known as:** DEBIAN-CVE-2026-26200, ECHO-a777-bf3c-cf20, GHSA-5p2m-j456-9mr2, JLSEC-2026-352, UBUNTU-CVE-2026-26200

## What is CVE-2026-26200?

CVE-2026-26200 is a high-severity memory corruption vulnerability in Hdfgroup Hdf5, published on 19 Feb 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

HDF5 is software for managing data. Prior to version 1.14.4-2, an attacker who can control an `h5` file parsed by HDF5 can trigger a write-based heap buffer overflow condition. This can lead to a denial-of-service condition, and potentially further issues such as remote code execution depending on the practical exploitability of the heap overflow against modern operating systems. Real-world exploitability of this issue in terms of remote-code execution is currently unknown. Version 1.14.4-2 fixes the issue.

Weakness: CWE-787 (Out-of-bounds Write), CWE-131 (Incorrect Calculation of Buffer Size), CWE-122 (Heap-based Buffer Overflow)

## Which versions are affected by CVE-2026-26200?

It affects 1 product.


Products: Hdfgroup Hdf5.

## How do I fix CVE-2026-26200?

Upgrade to a fixed version.

## Is CVE-2026-26200 being exploited?

There is no known exploitation of CVE-2026-26200 in the wild and no public exploit code.

## Other vulnerabilities in Hdfgroup Hdf5

- [CVE-2024-32608](https://insights.sbomify.com/CVE-2024-32608/): Memory corruption in n/a (critical 9.8)
- [CVE-2024-29157](https://insights.sbomify.com/CVE-2024-29157/): Memory corruption in n/a (critical 9.8)
- [CVE-2024-29159](https://insights.sbomify.com/CVE-2024-29159/): Memory corruption in n/a (critical 9.8)
- [CVE-2024-29164](https://insights.sbomify.com/CVE-2024-29164/): Memory corruption in n/a (critical 9.8)
- [CVE-2024-32611](https://insights.sbomify.com/CVE-2024-32611/): Other in n/a (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-26200 and fix it if it is affected.

What it is: CVE-2026-26200 is a high-severity memory corruption vulnerability in Hdfgroup Hdf5, published on 19 Feb 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: There is no known exploitation of CVE-2026-26200 in the wild and no public exploit code.

Affected product: Hdfgroup 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-2026-26200/ (Markdown: https://insights.sbomify.com/CVE-2026-26200/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-26200
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-26200
- OSV: https://osv.dev/vulnerability/CVE-2026-26200

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-26200/
Summaries are generated and may contain mistakes; the official description above is the record.