Exploitation evidence
Not listed in the latest downloaded CISA KEV catalog. This does not establish an absence of exploitation.
KEV checked 13 Nov 2026, 00:20 Jerusalem · Original catalog ↗Reported products and versions
The HDF Group / HDF5
Default status: unaffected
- affected: < 2.3.0
Fixes and workarounds
No explicit solution text in the downloaded CVE record. Consult the vendor advisory; unaffected version ranges are shown above as reported, not inferred as a patch recommendation.
Sources and related reporting
CVE Program record ↗ · Download tracked evidence as JSON
Monitored source mentions
Shared CVE identifiers link source mentions; they do not establish that the reports describe the same incident.
Observed change timeline
History begins when Egret first downloads each source. It is not the complete upstream CVE history.
12 Nov 2026, 18:20 Jerusalem · EPSS observation updated
Stored EPSS snapshot at this observation.
{
"date": "2026-11-12",
"epss": 0.00178,
"percentile": 0.07497
}11 Nov 2026, 12:20 Jerusalem · EPSS observation updated
Stored EPSS snapshot at this observation.
{
"date": "2026-11-10",
"epss": 0.00178,
"percentile": 0.07479
}11 Nov 2026, 12:20 Jerusalem · CVE Program record changed
Stored CNA snapshot at this observation.
{
"containers": {
"adp": [
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"metrics": [
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"other": {
"content": {
"id": "CVE-2026-120756",
"options": [
{
"Exploitation": "none"
},
{
"Automatable": "no"
},
{
"Technical Impact": "partial"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-11-03T17:55:08.252551Z",
"version": "2.0.3"
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"dateUpdated": "2026-11-03T17:55:20.773Z",
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"shortName": "CISA-ADP"
},
"title": "CISA ADP Vulnrichment"
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"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"modules": [
"Object Header"
],
"product": "HDF5",
"vendor": "The HDF Group",
"versions": [
{
"status": "affected",
"version": "< 2.3.0"
}
]
}
],
"descriptions": [
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"type": "text/html",
"value": "HDF5 through 2.2.0 contains a heap buffer over-read vulnerability in <code>H5O__chunk_deserialize()</code> in <code>src/H5Ocache.c</code>. 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 <code>H5O__mtime_new_decode()</code> in <code>src/H5Omtime.c</code>, to read beyond the heap allocation. The flaw is reachable during <code>H5Fopen()</code> 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. "
}
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}
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"impacts": [
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"capecId": "CAPEC-540",
"descriptions": [
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"lang": "en",
"value": "CAPEC-540 Overread Buffers"
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"Recovery": "NOT_DEFINED",
"Safety": "NOT_DEFINED",
"attackComplexity": "LOW",
"attackRequirements": "NONE",
"attackVector": "LOCAL",
"baseScore": 1.9,
"baseSeverity": "LOW",
"exploitMaturity": "PROOF_OF_CONCEPT",
"privilegesRequired": "NONE",
"providerUrgency": "NOT_DEFINED",
"subAvailabilityImpact": "NONE",
"subConfidentialityImpact": "NONE",
"subIntegrityImpact": "NONE",
"userInteraction": "PASSIVE",
"valueDensity": "NOT_DEFINED",
"vectorString": "CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:L/VI:N/VA:L/SC:N/SI:N/SA:N/E:P",
"version": "4.0",
"vulnAvailabilityImpact": "LOW",
"vulnConfidentialityImpact": "LOW",
"vulnIntegrityImpact": "NONE",
"vulnerabilityResponseEffort": "NOT_DEFINED"
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"format": "CVSS",
"scenarios": [
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"lang": "en",
"value": "GENERAL"
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],
"problemTypes": [
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"descriptions": [
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"cweId": "CWE-125",
"description": "CWE-125 Out-of-bounds read",
"lang": "en",
"type": "CWE"
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"dateUpdated": "2026-11-03T15:32:53.768Z",
"orgId": "0253b833-3e77-4dfe-9d57-17db1a2f0a74",
"shortName": "HDFG"
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"references": [
{
"url": "https://github.com/HDFGroup/hdf5/pull/6589"
},
{
"url": "https://github.com/HDFGroup/hdf5/issues/6401"
}
],
"source": {
"discovery": "UNKNOWN"
},
"title": "Heap Buffer Over-read via Malformed Message Size in HDF5's H5O__chunk_deserialize",
"x_generator": {
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"cveMetadata": {
"assignerOrgId": "0253b833-3e77-4dfe-9d57-17db1a2f0a74",
"assignerShortName": "HDFG",
"cveId": "CVE-2026-120756",
"datePublished": "2026-11-03T15:32:53.768Z",
"dateReserved": "2026-11-02T21:30:11.241Z",
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