---
id: CVE-2026-120499
title: h5io before 0.2.6 Arbitrary Code Execution via read_hdf5
summary: >-
  h5io before 0.2.6 contains a code injection vulnerability in read_hdf5() that
  allows attackers to execute arbitrary code by supplying a crafted HDF5 file.
  Attackers can store Python code in a node titled timezone, which
  _triage_read() pa…
severity: high
cvss: 7.8
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H'
cvssSource: cna
cwe:
  - CWE-95
  - CWE-502
vendor: h5io
product: h5io
affected:
  - h5io >= 0.1.0 < 0.2.6
ssvc:
  exploitation: poc
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-11-05T18:30:02.460697Z'
exploitAvailable: true
published: '2026-11-05'
updated: '2026-11-05'
sourceUpdated: '2026-11-05T18:30:58.290Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-120499'
references:
  - url: 'https://github.com/h5io/h5io/security/advisories/GHSA-vwvw-f6v4-w737'
    label: GitHub Security Advisory (GHSA-vwvw-f6v4-w737)
  - url: >-
      https://github.com/h5io/h5io/commit/afff1d61b31790f8c27e6c577bb7703eb1883ddd
  - url: 'https://github.com/h5io/h5io/releases/tag/h5io-0.2.6'
    label: h5io h5io-0.2.6 Release Notes
  - url: 'https://github.com/h5io/h5io/blob/h5io-0.2.5/h5io/_h5io.py#L601-L604'
  - url: >-
      https://www.vulncheck.com/advisories/h5io-before-0.2.6-arbitrary-code-execution-via-read-hdf5
    label: >-
      VulnCheck Advisory: h5io before 0.2.6 Arbitrary Code Execution via
      read_hdf5
tags:
  - cve.org
  - exploit-available
ingestedAt: '2026-11-05T22:38:31.470Z'
---

## Overview

h5io before 0.2.6 contains a code injection vulnerability in read_hdf5() that allows attackers to execute arbitrary code by supplying a crafted HDF5 file. Attackers can store Python code in a node titled timezone, which _triage_read() passes to eval() with builtins reachable, name an arbitrary module in class or custom-object nodes that _import_class() imports, or place pickled objects in pd_dataframe or pd_series nodes that pandas deserializes on read.

## Affected

- `h5io >= 0.1.0 < 0.2.6`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.