CVE-2026-34734

Q: How do I fix CVE-2026-34734?

Upgrade hdf5 to 1.14.1-2 or later.

Q: Is CVE-2026-34734 being actively exploited?

Not that we know of. CVE-2026-34734 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.19% is the estimated probability that it will be exploited in the next 30 days. That is higher than 9% of all scored CVEs.

Q: How severe is CVE-2026-34734?

CVE-2026-34734 has a CVSS v3 base score of 7.8, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.

Q: What does CVE-2026-34734 affect?

Published advisories record a fix for hdf5 (NVD). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.

HIGH

7.8

CVSS v3

NVD

Description

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.

CWE-416Use After Free CWE-825

How to fix

Remediation Available

hdf5NVD

Affected:< 1.14.1-2Fixed in:1.14.1-2CVE-2026-34734derived from NVD

TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorLocal

Attack ComplexityLow

Privileges RequiredNone

User InteractionRequired

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Exploit Intelligence

0.19%probability of exploitation in 30 days

9thpercentile

Low risk: more likely to be exploited than 9% of all known CVEs.

References

Exploit1

github.com

Other references3

Related Vulnerabilities

Other CWE-416 (Use After Free) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2019-0708	Critical	9.8	100%	KEV + Ransom	-
CVE-2021-31166	Critical	9.8	100%	KEV	Fix
CVE-2015-5119	Critical	9.8	99%	KEV	-
CVE-2010-3962	High	8.1	96%	KEV	-
CVE-2015-0313	Critical	9.8	96%	KEV	Fix
CVE-2021-34833	High	7.8	96%	-	-

Common questions

How do I fix CVE-2026-34734?

Upgrade hdf5 to 1.14.1-2 or later.

Is CVE-2026-34734 being actively exploited?

Not that we know of. CVE-2026-34734 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.19% is the estimated probability that it will be exploited in the next 30 days. That is higher than 9% of all scored CVEs.

How severe is CVE-2026-34734?

CVE-2026-34734 has a CVSS v3 base score of 7.8, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.

What does CVE-2026-34734 affect?

Published advisories record a fix for hdf5 (NVD). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.

Embed a live status badge for CVE-2026-34734

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-07-15.