Bug 2511855 (CVE-2026-19028)

Summary: CVE-2026-19028 hdf5: HDF5: Denial of Service via integer underflow in Fletcher32 filter
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: bbrownin
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in HDF5. An attacker can craft a malicious HDF5 file with a specially designed Fletcher32-filtered chunk. When this file is processed, an integer underflow occurs due to insufficient size validation, leading to a massive out-of-bounds read. This vulnerability can cause the application to crash, resulting in a denial of service.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
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Bug Depends On: 2515609, 2515610    
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Description OSIDB Bzimport 2026-08-05 23:21:20 UTC 
H5Z__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.