HDF5 integer underflow in Fletcher32 filter leads to massive out-of-bounds read

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-19028
StatePUBLISHED
AssignerHDFG
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-06 00:16:53 UTC
Updated2026-08-06 15:16:46 UTC
DescriptionH5Z__filter_fletcher32 in H5Zfletcher32.c in HDF5 through 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.

Risk And Classification

Primary CVSS: v4.0 6.8 MEDIUM from 0253b833-3e77-4dfe-9d57-17db1a2f0a74

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

EPSS: 0.001270000 probability, percentile 0.027190000 (date 2026-08-09)

Problem Types: CWE-125 | CWE-190 | CWE-1284 | CWE-190 CWE-190 Integer overflow or wraparound | CWE-125 CWE-125 Out-of-bounds read | CWE-1284 CWE-1284 Improper validation of specified quantity in input

VersionSourceTypeScoreSeverityVector
4.00253b833-3e77-4dfe-9d57-17db1a2f0a74Secondary6.8MEDIUMCVSS: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/C...
4.0CNACVSS6.8MEDIUMCVSS: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 v4.0 Breakdown

Attack Vector
Local
Attack Complexity
Low
Attack Requirements
None
Privileges Required
None
User Interaction
Passive
Confidentiality
None
Integrity
None
Availability
High
Sub Conf.
None
Sub Integrity
None
Sub Availability
None

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA The HDF Group HDF5 affected <=2.3.0 Not specified

References

ReferenceSourceLinkTags
github.com/HDFGroup/hdf5/issues/6488 134c704f-9b21-4f2e-91b3-4a467353bcc0 github.com
github.com/HDFGroup/hdf5/pull/6497 0253b833-3e77-4dfe-9d57-17db1a2f0a74 github.com
github.com/HDFGroup/hdf5/issues/6490 0253b833-3e77-4dfe-9d57-17db1a2f0a74 github.com
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