CVE-2026-26199: Hdfgroup HDF5

Medium severity, CVSS 6.5. EPSS: 0.4% chance of exploitation in the next 30 days.

HDF5 is a high-performance library and a file format specification that implements the HDF5 data model. If `H5Iget_name` is invoked on a group id with `0` for the size parameter, it will underflow when trying to place a null terminator in the buffer. This can occur if `H5Iget_name` is invoked in a way where `size` can be forced to zero, and there is important data before the `name` buffer.

Affected products

• Hdfgroup HDF5: before 2.1.0 (fixed in 2.1.0)

Published 2026-07-20. Last modified 2026-07-29.