CVE-2026-34734: HDF5 is software for managing data

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

hdf5: upgrade to 1.14.1-2. Exact commands for each OS are on this page.

Q: Is CVE-2026-34734 being exploited?

CVE-2026-34734 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-34734 affect?

CVE-2026-34734 affects hdf5. Severity is high (CVSS 7.8). 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

Q: How urgent is CVE-2026-34734?

Priority 35/100. High severity; Public exploit reference

Routine

HIGH 7.8UPGRADE

CVE-2026-34734 is a high-severity flaw (CVSS 7.8) affecting hdf5. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

High severity
Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	7.8 (High)
Attack vector	Local
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.2% (top 91%)
CISA exploited list	No
Weakness	CWE-416, CWE-825
Published	2026-04-09
Last modified	2026-10-26

Publisher (CNA): GitHub, Inc. · Vendor: hdfgroup

Last updated 2026-10-26 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-04-09 20:16 UTCPublished CVE record published
2026-10-26 21:10 UTCUpdated Record last modified

hdfgroup hdf5 UPGRADE

Affected: < 1.14.1-2

Fixed in: 1.14.1-2

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy hdf5 || rpm -q hdf5 || hdf5 --version

2. UPGRADE to 1.14.1-2 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade hdf5

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade hdf5

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-34734?

hdf5: upgrade to 1.14.1-2. Exact commands for each OS are on this page.

Is CVE-2026-34734 being exploited?

CVE-2026-34734 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-34734 affect?

CVE-2026-34734 affects hdf5. Severity is high (CVSS 7.8). 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

How urgent is CVE-2026-34734?

Priority 35/100. High severity; Public exploit reference

Related CVEs

CVE-2026-29043 MEDIUM 5.5 UPGRADE HDF5 is software for managing data
CVE-2026-26197 HIGH 7.5 UPGRADE HDF5 is a high-performance library and a file format specification that implements the HDF5 data model
CVE-2026-26199 MEDIUM 6.5 UPGRADE HDF5 is a high-performance library and a file format specification that implements the HDF5 data model
CVE-2026-17573 MEDIUM 5.5 UPGRADE A double free vulnerability was discovered in the HDF5 library
CVE-2026-17572 MEDIUM 5.5 UPGRADE Heap-based buffer overflow in the SOHM list-index deserialization code in HDF5 through 2.1.1 on all platforms

References

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