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VulnerabilityPublished Updated

CVE-2026-19026: The HDF Group HDF5 · NULL Pointer Dereference

Affects The HDF Group HDF5Source CVE Database V5

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Not known to be exploited · CVSS 6.8 Medium.

Data as of 3 Nov 2026, 22:58 UTC

CVSS 4.0 base score
6.8Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.1% chance of exploitation in 30 days – higher than 9% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 5 Aug 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 3 Nov 2026.

What to do

Affected software

ProductAffectedFixed in
The HDF GroupHDF5Affected
  • <=2.3.0
Fixed in–
GitHubhdfgroup/hdf5pkg:github/hdfgroup/hdf5Other threatsAffected
  • <=2.3.0
Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Until a fix is available, avoid processing untrusted HDF5 files that may contain crafted N-Bit filter pipeline messages with zero client-data values.

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.

References

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