Denial of Service Vulnerability in HDF5 by HDF Group

CVE-2026-19028

What is CVE-2026-19028?

The HDF5 library's H5Z__filter_fletcher32 function improperly computes data sizes when handling certain filtered chunks. Specifically, the function subtracts the size of a 4-byte trailing checksum from the input buffer size without verifying that the buffer is large enough to accommodate the operation. This oversight can lead to a size_t underflow, which attackers can exploit by crafting HDF5 files with insufficiently sized Fletcher32-filtered chunks. Exploiting this vulnerability may result in a denial of service, causing significant application crashes during operations such as H5Dread, and can be triggered using tools like h5ls or h5dump.

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