CVE-2026-19027: HDF5 out-of-bounds heap read in N-Bit filter decompression

The H5Znbitdecompressonebyte, H5Znbitdecompressonenooptype, and H5Znbitdecompressoneatomic functions in H5Znbit.c in HDF5 through 2.3.0 advance a read index into the compressed chunk buffer without bounding it against the buffer's actual size. This allows attackers to cause an out-of-bounds heap read, and in constrained cases disclosure of adjacent heap memory into decompressed dataset values, via a crafted HDF5 file whose N-Bit filter parameters describe more decompressed data than the stored compressed chunk actually contains, triggered via H5Dread, e.g. by the h5ls or h5repack tools.