CVE-2026-19026 Nbit filter NULL/short parameter-array dereference
Attackers can cause denial of service via crafted HDF5 files due to missing NULL checks in the Nbit filter.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-19026?
CVE-2026-19026 is a medium-severity vulnerability in The HDF Group HDF5, published on 5 Aug 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Official 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.
Which versions are affected by CVE-2026-19026?
How do I fix CVE-2026-19026?
Upgrade to a fixed version.
Is CVE-2026-19026 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-19026 exists.
Sources
Also known as AZL-94502, DEBIAN-CVE-2026-19026, ECHO-5628-d076-3b4e, GHSA-fr64-5gr2-c3jj, UBUNTU-CVE-2026-19026.