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NVD / CVE Program· CNA HDFG

CVE-2026-19027: HDF5 out-of-bounds heap read in N-Bit filter decompression

MediumCVSS 6.9 · v4.0—No exploit Fix available

Noroxi assessment

Priority: Monitor (action score 27/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.19% (FIRST EPSS).
  • Someone with local access to the system can trigger it. No account or password is required. No special conditions are required; it is repeatable.
  • Fixed version: azl3 hdf5 1.14.6-4 on Azure Linux 3.0 1.14.6-6; azl3 hdf5 1.14.6-6 on Azure Linux 3.0 1.14.6-6.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to azl3 hdf5 1.14.6-4 on Azure Linux 3.0 1.14.6-6; azl3 hdf5 1.14.6-6 on Azure Linux 3.0 1.14.6-6 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

The H5Z__nbit_decompress_one_byte, H5Z__nbit_decompress_one_nooptype, and H5Z__nbit_decompress_one_atomic functions in H5Znbit.c in HDF5 prior to 2.3.0 advance a read index into the compressed chunk buffer without bounding it against the buffer's actual size. This allows attackers to cause an out-of-bounds heap read, and in constrained cases disclosure of adjacent heap memory into decompressed dataset values, via a crafted HDF5 file whose N-Bit filter parameters describe more decompressed data than the stored compressed chunk actually contains, triggered via H5Dread, e.g. by the h5ls or h5repack tools.

Published
Aug 6, 2026
Updated
Oct 23, 2026
EPSS
0.1% · 9th percentile

Report tools

JSON

Action score

27

Monitor

Low priority for now.

CVSS
27 / 40 · 6.9 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

CISA SSVC decision

Exploitation
proof of concept
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · HDFG
6.9
NVD has not scored this yet; the score shown is the CNA’s.

CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:L/VI:N/VA:H/SC:N/SI:N/SA:N

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2026-19027

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

—

Versions reported by the vendor

Affected version ranges reported by the assigning authority (HDFG). Independent of NVD's CPE analysis and usually ahead of it.

  • The HDF Group HDF5

    • <=2.3.0affected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12hdf5from 0—
Red Hat:hummingbird:1hdf5before 0:2.2.0-0.1.2.hum10:2.2.0-0.1.2.hum1
Red Hat:hummingbird:1hdf5-develbefore 0:2.2.0-0.1.2.hum10:2.2.0-0.1.2.hum1
Red Hat:hummingbird:1hdf5-mpichbefore 0:2.2.0-0.1.2.hum10:2.2.0-0.1.2.hum1
Red Hat:hummingbird:1hdf5-mpich-develbefore 0:2.2.0-0.1.2.hum10:2.2.0-0.1.2.hum1
Red Hat:hummingbird:1hdf5-mpich-staticbefore 0:2.2.0-0.1.2.hum10:2.2.0-0.1.2.hum1
Red Hat:hummingbird:1hdf5-openmpibefore 0:2.2.0-0.1.2.hum10:2.2.0-0.1.2.hum1
Red Hat:hummingbird:1hdf5-openmpi-develbefore 0:2.2.0-0.1.2.hum10:2.2.0-0.1.2.hum1
Red Hat:hummingbird:1hdf5-openmpi-staticbefore 0:2.2.0-0.1.2.hum10:2.2.0-0.1.2.hum1
Red Hat:hummingbird:1hdf5-staticbefore 0:2.2.0-0.1.2.hum10:2.2.0-0.1.2.hum1
Red Hat:hummingbird:1java-hdf5before 0:2.2.0-0.1.2.hum10:2.2.0-0.1.2.hum1

Same product

the hdf group: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-106547HDF5 heap buffer overflow in H5VM_array_fill via crafted fill-value metadata
    34Monitor
  • CVE-2026-19024HDF5 H5Pget_fill_value NULL Pointer Dereference via Malformed Fill Value Message
    32Monitor
  • CVE-2026-19029HDF5 scale-offset filter heap buffer over-read via crafted chunk
    27Monitor

Published before and after this one in the same product

  • ← EarlierCVE-2026-19025Aug 5, 2026 · HDF5 divide-by-zero (SIGFPE) via mismatched chunk-layout dimensionality and dataspace rank on dataset open
    27Monitor
  • ← EarlierCVE-2026-19026Aug 5, 2026 · Nbit filter NULL/short parameter-array dereference
    27Monitor
  • Later →CVE-2026-19028Aug 6, 2026 · HDF5 integer underflow in Fletcher32 filter leads to massive out-of-bounds read
    27Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
azl3 hdf5 1.14.6-4 on Azure Linux 3.01.14.6-6 · Release NotesMicrosoft (MSRC)
azl3 hdf5 1.14.6-6 on Azure Linux 3.01.14.6-6 · Release NotesMicrosoft (MSRC)
red hat:hdf50:2.2.0-0.1.2.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:hdf5-devel0:2.2.0-0.1.2.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:hdf5-mpich0:2.2.0-0.1.2.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:hdf5-mpich-devel0:2.2.0-0.1.2.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:hdf5-mpich-static0:2.2.0-0.1.2.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:hdf5-openmpi0:2.2.0-0.1.2.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:hdf5-openmpi-devel0:2.2.0-0.1.2.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:hdf5-openmpi-static0:2.2.0-0.1.2.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:hdf5-static0:2.2.0-0.1.2.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:java-hdf50:2.2.0-0.1.2.hum1 · Red Hat:hummingbird:1Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2026-190280 days apartHDF5 integer underflow in Fletcher32 filter leads to massive out-of-bounds read
    27Monitor
  • CVE-2026-1902961 days apartHDF5 scale-offset filter heap buffer over-read via crafted chunk
    27Monitor

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

Not on record for this CVE: researcher credit · public bounty program.

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • No account or password is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
Integrity
Availability
Attack vector
Local
Attack complexity
Low
Privileges required
None
User interaction
P
Scope
X

Weakness class (CWE)

CWE-125 · Out-of-bounds Read

CVSS vector

CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:L/VI:N/VA:H/SC:N/SI:N/SA:N/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

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

—

References

Show all references (2 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records