Skip to content
Noroxi
NVD / CVE Program· CNA HDFG

CVE-2026-19028: HDF5 integer underflow in Fletcher32 filter leads to massive out-of-bounds read

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

H5Z__filter_fletcher32 in H5Zfletcher32.c in HDF5 prior to 2.3.0 computes the data length to checksum by subtracting the 4-byte trailing checksum size from the input buffer size without checking that the buffer is at least 4 bytes, allowing a size_t underflow. This allows attackers to cause a denial of service (massively out-of-bounds read and application crash in H5_checksum_fletcher32) via a crafted HDF5 file with a Fletcher32-filtered chunk smaller than 4 bytes, triggered via H5Dread, e.g. by the h5ls or h5dump tools.

MediumCVSS 6.8 · v4.0—No exploit Fix available
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 · 6.8 / 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
6.8
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:N/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-2026-19028

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

One daily email digest (06:00 UTC); connect a webhook for KEV listings and weaponized exploits instantly.

Your free account also gets you

Running WordPress? Scan your site free with WP Lens

  • Stack alerts: add the products and versions you run, get the new CVEs that affect them
  • Uptime monitoring: 1 site, instant email when it goes down
  • Add your domain: subdomains and takeover risk scanned every week (1 domain)
  • 10 scans an hour on the security tools (3 a day without an account), an API key and MCP
  • All your scans in one panel: findings, what changed in the last scan, a report per domain or per client (PDF, share link)
All free tools

Sign up with email · Have an account? Sign in

Free account, no card. Unfollow any time.

Don't want an account? Get "Exploited this week" by email every MondayDon't want an account? RSS feed for the hdf group records

Running WordPress? Scan your site free with WP Lens

Is your version affected? Check it

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.

We use this product, ask for help

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-2026-19026Aug 5, 2026 · Nbit filter NULL/short parameter-array dereference
    27Monitor
  • ← EarlierCVE-2026-19027Aug 6, 2026 · HDF5 out-of-bounds heap read in N-Bit filter decompression
    27Monitor
  • Later →CVE-2026-92627Sep 16, 2026 · Heap Use-After-Free in H5T__conv_f_f
    18Monitor

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.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

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

  • CVE-2026-190270 days apartHDF5 out-of-bounds heap read in N-Bit filter decompression
    27Monitor
  • CVE-2026-1902961 days apartHDF5 scale-offset filter heap buffer over-read via crafted chunk
    27Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

National notice (Türkiye Cybersecurity Directorate / USOM)

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

All national notices →

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:N/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

—

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (2 more)

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

All records