CVE-2026-19028

Name of the Vulnerable Software and Affected Versions HDF5 versions prior to 2.3.1

Description A size t underflow occurs in the H5Z filter fletcher32 function within H5Zfletcher32.c. The issue arises when the software computes the data length to checksum by subtracting the 4-byte trailing checksum size from the input buffer size without verifying that the buffer is at least 4 bytes. An attacker can exploit this by providing a crafted HDF5 file containing a Fletcher32-filtered chunk smaller than 4 bytes, which is triggered via the H5Dread function (for example, when using h5ls or h5dump tools). This leads to a massive out-of-bounds read in the H5 checksum fletcher32 function, resulting in a denial of service and application crash.

Recommendations Update to version 2.3.1 or later.