# CVE-2026-29043: HDFGroup HDF5 heap buffer overflow in H5T__ref_mem_setnull

Source: https://junglewise.ai/threats/cve-2026-29043-hdfgroup-hdf5-heap-buffer-overflow-in-h5t-ref-mem-setnull  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-04-10. Updated: 2026-05-10  
License: CC BY 4.0 with a link back

CVE-2026-29043 · Severity: medium · CVSS 5.5 · Published 2026-04-10

HDF5 is a widely used library and file format for managing and storing large amounts of complex data. A vulnerability exists where a specially crafted data file can cause the software to crash or behave unexpectedly when opened. This could lead to a service outage or, in some cases, allow an attacker to gain unauthorized control over the system processing the file.

Technologies: [Hdfgroup Hdf5](https://junglewise.ai/threats/technologies/hdf5). Vendors: [Hdfgroup](https://junglewise.ai/threats/vendors/hdfgroup).

## Quick answers

**Is CVE-2026-29043 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-29043 being exploited in the wild.

**How severe is CVE-2026-29043?** Medium severity, with a CVSS score of 5.5, published 10 April 2026.

**Which products and versions are affected?** HDFGroup HDF5 <= 1.14.1-2.

**Is there a fix for CVE-2026-29043?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-29043 attacked?** It is attacked with local access, in a software library.

**Am I affected by CVE-2026-29043?** Check whether you run Hdfgroup Hdf5. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A heap-based buffer overflow (CWE-122) exists in HDF5 versions 1.14.1-2 and earlier within the H5T__ref_mem_setnull method. The vulnerability is triggered when the library parses a maliciously crafted .h5 file, specifically during memory initialization where the method attempts to overwrite target buffers with null bytes. While the attack typically requires a user to open a malicious file using utilities like h5dump or h5stat (requiring User Interaction), it could also impact server-side processes that automatically parse user-supplied HDF5 files. Successful exploitation can lead to a denial-of-service (DoS) via application crash or potentially remote code execution (RCE), though the nature of the null-byte write may complicate RCE exploitation on modern systems. As of the advisory date, no patched version has been specified.

## Affected products

- HDFGroup HDF5 <= 1.14.1-2

## Timeline

- 2026-04-10: advisory: Initial advisory published by GitHub and HDFGroup
- 2026-04-10: disclosed: CVE-2026-29043 assigned

## References

- [https://github.com/HDFGroup/hdf5/security/advisories/GHSA-qm2m-5g5w-2277](https://github.com/HDFGroup/hdf5/security/advisories/GHSA-qm2m-5g5w-2277)

## Related threats

- [HDF5 NULL pointer dereference in H5HL_unprotect](https://junglewise.ai/threats/cve-2026-120758-hdf5-through-2-2-0-contains-a-null-pointer-dereference)
- [HDF5 heap buffer over-read in object header deserialization](https://junglewise.ai/threats/cve-2026-120756-hdf5-through-2-2-0-contains-a-heap-buffer-over-read)
- [HDF5 out-of-bounds read in szip filter](https://junglewise.ai/threats/cve-2026-120755-hdf5-through-2-2-0-contains-an-out-of-bounds-read-vulnerability)
- [HDF5 uncontrolled recursion in B-tree iteration](https://junglewise.ai/threats/cve-2026-120689-hdf5-through-2-2-0-contains-an-uncontrolled-recursion)
- [HDFGroup HDF5 heap use-after-free in h5dump utility](https://junglewise.ai/threats/cve-2026-34734-hdfgroup-hdf5-heap-use-after-free-in-h5dump-utility)