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Fencer Vulns
high 7.8

CVE-2026-34734 json

HDF5: H5T__conv_struct Use After Free

published 2026-04-09 7 mo ago modified 2026-10-26 13 d ago also EUVD-2026-21020 , JLSEC-2026-354

cvss
7.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 9%
public exploits
0
none known

Summary

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.

Patch / fix

  • julia HDF5_jll 1.14.2+0
  • hdf5 hummingbird 1 2.2.0-0.1.1.hum1
  • java-hdf5 hummingbird 1 2.2.0-0.1.1.hum1
  • hdf5-mpich hummingbird 1 2.2.0-0.1.1.hum1
  • hdf5-openmpi hummingbird 1 2.2.0-0.1.1.hum1

red hat advisories RHSA-2026:61630

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-34734 updated cvss 7.8

hdf5: HDF5 h5dump: Arbitrary code execution via a crafted HDF5 file

  • Red Hat Enterprise Linux AI (RHEL AI) 3 hdf5
    affected: workaround, no fix available
  • Red Hat Hardened Images hdf5 2.2.0-0.1.1.hum1, java-hdf5 2.2.0-0.1.1.hum1, hdf5-mpich 2.2.0-0.1.1.hum1, hdf5-openmpi 2.2.0-0.1.1.hum1
    fixed: vendor fix RHSA-2026:61630

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
total
Assessed
6 mo ago

Exploit prediction

0.20% chance of exploitation in the next 30 days, higher than 9% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/HDFGroup/hdf5/security/advisories/GHSA-w7v2-9cmr-pwwj referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
CISA ADP 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
OSV 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Affected packages

ecosystem package affected fixed in
julia HDF5_jll
<1.14.2+0
1.14.2+0

Affected products

  • HDFGroup hdf5
  • Red Hat Red Hat Enterprise Linux AI (RHEL AI) 3

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.