# HDF4 4.0 Release

**URL:** <https://forum.hdfgroup.org/t/hdf4-4-0-release/13878>\
**Category:** News and Announcements\
**Created:** [September 4, 2026, 10:21pm UTC](https://forum.hdfgroup.org/t/hdf4-4-0-release/13878 "2026-09-04T22:21:16Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![bmribler](https://forum.hdfgroup.org/letter_avatar_proxy/v4/letter/b/a6a055/32.png) [@bmribler](https://forum.hdfgroup.org/u/bmribler)\
**Post date:** [September 4, 2026, 10:21pm UTC](https://forum.hdfgroup.org/t/hdf4-4-0-release/13878/1 "2026-09-04T22:21:16Z")

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We have released HDF4 4.0 this week. It is going to be the last official release of the HDF4 library. In this release, we have

- moved to build with CMake exclusively
- addressed many memory issues and security vulnerabilities
- resolved various issues involving how reading szipped data and the availability of the szip/aec libraries work together
- hardened error handling and resource cleanup in tests and tools for improved security and better maintainability
- removed outdated NetCDF interface

There are breaking changes to address vulnerabilities. Please refer to the [RELEASE.txt](https://github.com/HDFGroup/hdf4/blob/2c46ad5/release_docs/RELEASE.txt) for details.

Please find out more in our [blog post](https://www.hdfgroup.org/2026/09/03/oldie-but-a-goodie/).

Thank you!