CVE-2026-19026: Nbit filter NULL/short parameter-array dereference

Severity: medium (CVSS 6.8 v4.0)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-08-05 · updated 2026-10-23
Weakness: CWE-476

Description

H5Z__filter_nbit in H5Znbit.c in HDF5 prior to 2.3.0 dereferences cd_values[0] through cd_values[4] without validating that cd_values is non-NULL or that cd_nelmts 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.

Affected products

HDF5: through 2.3.0

References

https://github.com/HDFGroup/hdf5/issues/6489
https://github.com/HDFGroup/hdf5/issues/6492
https://github.com/HDFGroup/hdf5/pull/6497
https://github.com/HDFGroup/hdf5/issues/6489

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