CVE-2026-19028Public exploit

Application crash via Fletcher32 checksum length underflow

Published Aug 5, 2026 · Updated Aug 5, 2026

Out-of-bounds read in The HDF Group HDF5 2.3.0 and earlier allows attackers to crash a reader by supplying a crafted HDF5 file. H5Z__filter_fletcher32 subtracts the four-byte checksum length from an unchecked shorter chunk size, wraps size_t, and passes the huge length to H5_checksum_fletcher32. A user or service must process a Fletcher32-filtered chunk under four bytes through H5Dread; the reported consequence is an application crash, not data disclosure or modification.

CVSS severity6.8
Medium
EPSS probability0.13%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds read in The HDF Group HDF5 2.3.0 and earlier allows attackers to crash a reader by supplying a crafted HDF5 file. H5Z__filter_fletcher32 subtracts the four-byte checksum length from an unchecked shorter chunk size, wraps size_t, and passes the huge length to H5_checksum_fletcher32. A user or service must process a Fletcher32-filtered chunk under four bytes through H5Dread; the reported consequence is an application crash, not data disclosure or modification.

The record

CVE
CVE-2026-19028
Published
Aug 5, 2026
Updated
Aug 5, 2026
Vendor
The HDF Group
Product
HDF5
Classifications
CWE-1284, CWE-125, CWE-190, T1499.004
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 5, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 5, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=<=2.3.0

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

The HDF Group · HDF5version=<=2.3.0

Published CVSS scores

6.8HDFGCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-1284Improper Validation of Specified Quantity in Input
CWE-125Out-of-bounds Read
CWE-190Integer Overflow or Wraparound
T1499.004Endpoint Denial of Service: Application or System Exploitation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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