OESA-2026-4606: hdf5 security update

HDF5 is a data model, library, and file format for storing and managing data. It supports an unlimited variety of datatypes, and is designed for flexible and efficient I/O and for high volume and complex data. HDF5 is portable and is extensible, allowing applications to evolve in their use of HDF5. The HDF5 Technology suite includes tools and applications for managing, manipulating, viewing, and analyzing data in the HDF5 format. Security Fix(es):

Untrusted pointer dereference in the renderbinoutput function in the h5dump tool in HDF5 before 2.3.0 allows attackers to cause a denial of service via a variable-length string dataset with more than one element dumped in binary mode, which corrupts the per-element stride calculation and causes subsequent elements to be read from a misaligned offset and dereferenced as a pointer.(CVE-2026-19023)

NULL pointer dereference in H5Pgetfillvalue in HDF5 before 2.3.0 allows attackers to cause a denial of service via a dataset whose version 1 or 2 fill value message has the "defined" flag set together with a negative size field, which is not normalized to the library's "undefined" sentinel and reaches H5Tpathfind with a NULL datatype.(CVE-2026-19024)

H5Zfilternbit in H5Znbit.c in HDF5 prior to 2.3.0 dereferences cdvalues[0] through cdvalues[4] without validating that cdvalues is non-NULL or that cdnelmts is at least 5, the fixed size of the filter's header. This allows attackers to cause a denial of service via a crafted HDF5 file that stores the N-Bit filter pipeline message with zero client-data values, opened and read via H5Dread, e.g. by the h5ls or h5repack tools.(CVE-2026-19026)

The H5Znbitdecompressonebyte, H5Znbitdecompressonenooptype, and H5Znbitdecompressoneatomic functions in H5Znbit.c in HDF5 prior to 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.(CVE-2026-19027)

H5Zfilterfletcher32 in H5Zfletcher32.c in HDF5 prior to 2.3.0 computes the data length to checksum by subtracting the 4-byte trailing checksum size from the input buffer size without checking that the buffer is at least 4 bytes, allowing a sizet underflow. This allows attackers to cause a denial of service (massively out-of-bounds read and application crash in H5checksumfletcher32) via a crafted HDF5 file with a Fletcher32-filtered chunk smaller than 4 bytes, triggered via H5Dread, e.g. by the h5ls or h5dump tools.(CVE-2026-19028)