The missing EPSS score for this HDF5 NULL dereference is a red herring. What actually matters is understanding what this vulnerability IS: a crash triggered not by malicious exploitation, but by malformed .h5 files with an inconsistent internal 'defined' flag and negative size. The CVSS likely scores this HIGH with LOW attack complexity—and that LOW complexity is the critical signal. Because the trigger is malformed file data rather than intentional exploitation, any downstream tool calling H5Dread() or H5Dwrite() on untrusted scientific datasets will hit this crash surface repeatedly in production. Your HPC cluster that ingests climate data from external collaborators? Your image processing pipeline that loads microscopy datasets? These are the real exposure, and they have nothing to do with attack chains or threat intelligence feeds. Here is what makes this urgent despite the likely low EPSS once it publishes: HDF5 exposes no sanitize-or-validate API. There is no H5Pset_strict_parsing() flag, no H5Fvalidate() call that lets a consumer check file structural integrity before passing it to the library. The crash happens inside libhdf5, not in your error-handling path. This means you cannot defend against it with input filtering—you can only patch. If your environment ingests .h5 files from any source you do not fully control, treat this as a priority-1 patch regardless of EPSS. The prioritization signal is not the scoring feeds—it is whether your specific deployment model matches the attack surface: shared filesystems in HPC, containerized ingestion pipelines, or any workflow where external collaborators push datasets into your processing chain.
CVE-2026-19024
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedNULL pointer dereference in H5Pget_fill_value 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 H5T_path_find with a NULL datatype.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysisThe code follows a pointer that is null, crashing the process. An attacker who can reliably trigger it turns the crash into a denial of service. The fix is checking for null before use and handling the failure path gracefully.
General guidance for the null pointer dereference class — the official description and references above are authoritative for this specific CVE. Want a bespoke review and a reviewed fix? Ask our team →
CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Local
- Complexity
- Low
- Privileges
- None
- Authentication
- X
- User interaction
- P
- Scope
- X
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scopedHDF5 2.1.1 or later
- 1. Identify the current HDF5 library version in use by running `h5dump --version` or checking your project's dependency management system
- 2. If the version is earlier than 2.1.1, obtain HDF5 version 2.1.1 or later from the official HDF5 repository at github.com/HDFGroup/hdf5
- 3. Rebuild and redeploy any applications or libraries that link against the HDF5 library
- 4. Test that H5Pget_fill_value functions correctly with datasets that have fill value messages
Generated from the published advisory — verify against the referenced sources before acting.
There is no version to upgrade to and no patch to apply. Every affected install stays exposed until the vendor ships a fix — or somebody else builds one.
Free. We build fixes in the order the community asks for them — and we’ll tell you the moment this one lands.
We develop and verify an original fix where the vendor hasn’t, from $3,200. Deployed to your staging first — never straight to production.
Scope it with usSee what else the community needs solved on the solutions-needed board.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-19024 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesThe missing EPSS score for this HDF5 NULL dereference is a red herring. What actually matters is understanding what this vulnerability IS: a crash triggered not by malicious exploitation, but by malformed .h5 files with an inconsistent internal 'defined' flag and negative size. The CVSS likely scores this HIGH with LOW attack complexity—and that LOW complexity is the critical signal. Because the trigger is malformed file data rather than intentional exploitation, any downstream tool calling H5Dread() or H5Dwrite() on untrusted scientific datasets will hit this crash surface repeatedly in production. Your HPC cluster that ingests climate data from external collaborators? Your image processing pipeline that loads microscopy datasets? These are the real exposure, and they have nothing to do with attack chains or threat intelligence feeds. Here is what makes this urgent despite the likely low EPSS once it publishes: HDF5 exposes no sanitize-or-validate API. There is no H5Pset_strict_parsing() flag, no H5Fvalidate() call that lets a consumer check file structural integrity before passing it to the library. The crash happens inside libhdf5, not in your error-handling path. This means you cannot defend against it with input filtering—you can only patch. If your environment ingests .h5 files from any source you do not fully control, treat this as a priority-1 patch regardless of EPSS. The prioritization signal is not the scoring feeds—it is whether your specific deployment model matches the attack surface: shared filesystems in HPC, containerized ingestion pipelines, or any workflow where external collaborators push datasets into your processing chain.
Practitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-19024 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.
- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
- No spam, self-promotion, credentials, or personal data