HDF5 is software for managing data. In 1.14.1-2 and earlier, an attacker who can control an h5 file parsed by HDF5 can trigger a write-based heap buffer overflow condition in the H5T ref mem setnull method. 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.