Bug 2566025 (CVE-2026-120756)

Summary: CVE-2026-120756 hdf5: hdf5: Denial of Service via heap buffer over-read
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, eglynn, jjoyce, jpretori, jschluet, lhh, mburns, mgarciac
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in hdf5. When parsing object header messages, insufficient boundary checks can allow an attacker to trigger a heap buffer over-read by convincing a user or application to open a specially crafted file. Successful exploitation could cause the application to crash, resulting in a Denial of Service (DoS), or potentially lead to limited disclosure of process memory.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Bug Depends On: 2566128, 2566129    
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Description OSIDB Bzimport 2026-11-03 17:39:47 UTC 
HDF5 through 2.2.0 contains a heap buffer over-read vulnerability in H5O__chunk_deserialize() in src/H5Ocache.c. When decoding object header messages, the declared message size is checked against the end of the chunk image before the remainder of the message header (flags, and for version 2 object headers, the optional creation index) has been decoded. Because the message body begins after these fields, a message can start up to four bytes further into the chunk than the size check accounts for. A crafted HDF5 file can declare a message size that passes the check but extends past the end of the chunk image, causing the message’s decode callback, for example H5O__mtime_new_decode() in src/H5Omtime.c, to read beyond the heap allocation. The flaw is reachable during H5Fopen() on a crafted file. An attacker who can get a user or application to open a malicious file can cause a denial of service or limited disclosure of process memory.