CVE-2025-6856Public exploit

Local process crash via freed free-list node

Published Jun 29, 2025 · Updated Jun 30, 2025

Use-after-free in HDF5 1.14.6 allows local users to crash a linked process by supplying a crafted HDF5 file for parsing. H5FL__reg_gc_list traverses a regular-block free list during library shutdown and reads a next-node pointer from an entry freed by the same loop. The input must reach H5Fopen and create corrupted object-header continuation state; the demonstrated consequence is a heap-use-after-free and process termination.

CVSS severity3.3
Low
EPSS probability0.21%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in HDF5 1.14.6 allows local users to crash a linked process by supplying a crafted HDF5 file for parsing. H5FL__reg_gc_list traverses a regular-block free list during library shutdown and reads a next-node pointer from an entry freed by the same loop. The input must reach H5Fopen and create corrupted object-header continuation state; the demonstrated consequence is a heap-use-after-free and process termination.

The record

CVE
CVE-2025-6856
Published
Jun 29, 2025
Updated
Jun 30, 2025
Vendor
The HDF Group
Product
HDF5
Classifications
CWE-119, CWE-416
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 29, 2025CVE publishedPublication date reported by the CVE source.
  2. Jun 30, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=1.14.6

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The HDF Group · HDF5version=1.14.6

Published CVSS scores

1.9VulDBCVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P
3.3VulDBCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
7.8NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
1.7VulDBAV:L/AC:L/Au:S/C:N/I:N/A:P

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-119Improper Restriction of Operations within the Bounds of a Memory Buffer
CWE-416Use After Free

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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