What is CVE-2026-19026?
H5Z__filter_nbit in H5Znbit.c in HDF5 through 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.
The record classifies CVE-2026-19026 under weakness classes CWE-476, CWE-1284. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 61 days ago.
Severity and exploitation probability
- CVSS v4.0 base score
- 6.8 — Medium (derived from score)
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 - EPSS (FIRST)
- 0.1% probability of exploitation in the next 30 days, higher than 2.7% of all scored CVEs
- CISA KEV
- Not listed in the CISA Known Exploited Vulnerabilities catalog
- Threadlinqs priority
- 3.5/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- Published
- 2026-08-05, last modified 2026-08-06
Is CVE-2026-19026 being exploited?
It currently carries a trending score of 30 in the Threadlinqs vulnerability feed.
Affected products and versions
- The HDF Group: HDF5
How to fix CVE-2026-19026
No vendor patch reference has been recorded for CVE-2026-19026 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.
Threat activity tracking CVE-2026-19026
No threat campaign in the Threadlinqs corpus currently references CVE-2026-19026, in its CVE list or as an indicator. The linkage is recomputed from the live corpus on every daily ingest, so this section fills in as soon as a tracked campaign cites the identifier.
Sources
Enriched from CVE.org, FIRST EPSS, GitHub Security Advisories. Last verified by Threadlinqs on .