What is the CVSS score of EUVD-2026-21020?

EUVD-2026-21020 has a CVSS 3.1 base score of 7.8 (High). CVSS vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H. EPSS exploitation probability: 0.0%.

How to fix or mitigate EUVD-2026-21020?

Within 24 hours: identify all systems running HDF5 versions 1.14.1-2 or earlier using software inventory tools; notify data stewards and researchers to suspend opening HDF5 files from untrusted sources. Within 7 days: implement file-source validation policies; restrict h5dump execution to isolated environments or dedicated analysis systems; establish user awareness training on malicious file risks. Within 30 days: monitor HDFGroup for patch release to version 1.14.2 or later; test patch in development environment; deploy to production systems following change management protocols.

Hdf5 EUVD-2026-21020

| CVE-2026-34734 HIGH

Use After Free (CWE-416)

2026-04-09 GitHub_M

Information Disclosure Use After Free Memory Corruption Hdf5 Hdfgroup

7.8

CVSS 3.1 · Vendor: GitHub_M

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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

Access

Supply malicious HDF5 file to h5dump
Delivery

Trigger H5D__typeinfo_init_phase3 allocation
Exploit

H5D__typeinfo_term frees object prematurely
Execution

memmove references freed memory
Impact

Execute arbitrary code

Vulnerability Assessment

Weakness	CWE CWE-416 ASVS 5.0 V15 - Secure Coding and Architecture Memory lifecycle management MITRE ATT&CK 2 techniques across 2 tactics: Execution, Privilege Escalation The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. Sign in to read
Exploitation Conditions	Local attacker supplies malicious HDF5 file to victim running h5dump utility (HDF5 versions 1.14.1-2 and earlier). Victim must open/process the crafted .h5 file with h5dump. No authentication required. Heap-use-after-free in H5T__conv_struct conversion function triggers memory corruption.
Impact	CVSS 7.8 reflects high severity heap use-after-free in h5dump requiring local file access and user interaction. EPSS and KEV data unavailable. Blast radius limited to systems processing untrusted HDF5 files locally; no network vector. Critical for research/scientific workflows handling external datasets, less urgent for isolated deployments.
Exploit ScenarioDerived	Attacker crafts malicious HDF5 file triggering heap-use-after-free during h5dump parsing. User opens file locally; h5dump dereferences freed memory in H5T__conv_struct memmove, causing crash or memory corruption. No public exploit identified at time of analysis.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).

Patch available 0.0% exploitation probability (EPSS)

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AnalysisAIv1 – Apr 09, 2026

Heap use-after-free in HDF5 h5dump utility allows local attackers to achieve arbitrary code execution when processing malicious HDF5 files. Affects HDF5 versions 1.14.1-2 and earlier from HDFGroup. Attacker must convince user to open crafted file (user interaction required, CVSS UI:R). Unauthenticated attack vector enables high-impact compromise of confidentiality, integrity, and availability. No public exploit identified at time of analysis. Vulnerability stems from premature deallocation in H5D__typeinfo_term followed by unsafe reference in H5T__conv_struct memmove operation.

RemediationAI

No vendor-released patch identified at time of analysis. Monitor HDFGroup security advisory at https://github.com/HDFGroup/hdf5/security/advisories/GHSA-w7v2-9cmr-pwwj for patch availability and upgrade guidance. Until patched version releases, restrict h5dump usage to trusted HDF5 files only. Implement input validation controls to block untrusted file processing. Deploy h5dump in sandboxed environments with limited privileges to contain potential exploitation. Consider disabling h5dump utility in production environments where file provenance cannot be verified. Organizations should establish file validation procedures and security awareness training regarding risks of opening HDF5 files from untrusted sources.

Affected VersionsENISA

HDF5 ≤ 1.14.1-2

Affected Packages

euvd hdf5 no fix

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

CWE-416 use-after-free occurs when H5D__typeinfo_init_phase3 allocates heap object later freed by H5D__typeinfo_term, then H5T__conv_struct references freed memory via memmove during struct conversion. Temporal gap between deallocation and reference creates exploitable window for memory manipulation through malformed HDF5 file structures processed by h5dump helper utility.

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

Vendor (GitHub_M) PRIMARY 7.8 HIGH

AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

SUSE HIGH

Red Hat 7.8 HIGH

Primary rating from Vendor (GitHub_M).

CVSS VectorVendor: GitHub_M

Attack Vector

Local

Attack Complexity

Low

Privileges Required

None

User Interaction

Required

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

DescriptionCVE.org

HDF5 is software for managing data. In 1.14.1-2 and earlier, a heap-use-after-free was found in the h5dump helper utility. An attacker who can supply a malicious h5 file can trigger a heap use-after-free. The freed object is referenced in a memmove call from H5T__conv_struct. The original object was allocated by H5D__typeinfo_init_phase3 and freed by H5D__typeinfo_term.

Executive ViewAI

Why It Matters

CVE-2026-34734 is a heap use-after-free vulnerability in HDF5's h5dump utility (versions 1.14.1-2 and earlier) that allows local attackers to execute arbitrary code by inducing users to open malicious HDF5 files. Organizations using HDF5 for scientific data processing, climate modeling, or geospatial analysis face potential compromise of sensitive research data and system integrity without immediate patching options.

Business Impact: High

Compensating Controls

No vendor-released patch identified at time of analysis. Interim mitigations: (1) Restrict h5dump execution to non-networked systems or air-gapped analysis environments; (2) Implement strict file-source controls-only process HDF5 files from verified, trusted sources with documented provenance; (3) Run h5dump within containerized or virtualized isolation (Docker, VM) to limit code execution scope; (4) Disable h5dump where operationally feasible, replacing with read-only alternative tools; (5) Monitor for unexpected process termination or segmentation faults in HDF5 processing workflows as indicators of exploitation attempts.

Threat Intelligence Overview

EPSS Score

0.0%

Top 98% exploitable

Data Quality

8 sources

Confidence: High

EUVD

NVD

CVE.org

EPSS

Vulnrichment Vendor

GitHub

VulDB

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue

Severity HIGH

CISA KEV No

Public POC No

EPSS 0.0%

Patch available Yes

Active threat No

Deciding rule

HIGH severity (CVSS 7.0-8.9)

What every action level means

Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.

Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.

This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.

This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.

Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision

Scheduled

Exploitation

Poc

System Exposure· derived

Small

Automatable

Human Impact

High

Technical Impact

Total

Priority Score

Low Medium High Critical

KEV: 0

EPSS: 0

CVSS: +39

PoC: 0

Weaponized: 0

Threat intel: 0

Gov advisory: 0

Attack Technique

Use After Free HIGH

Use-after-free vulnerabilities occur when a program continues to access memory through a pointer after that memory has been deallocated.

Memory Corruption HIGH

Memory corruption occurs when a program writes data beyond the boundaries of allocated memory regions or accesses memory in unintended ways, violating the integrity of the process's address space.

Information Disclosure MEDIUM

Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.