Vulnerability · Published Nov 5, 2026 · Assigned by VulnCheck

CVE-2026-120499h5io before 0.2.6 Arbitrary Code Execution via read_hdf5

High 7.8

In plain English

A high-severity unsafe deserialization in h5io from h5io. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 37% of all known vulnerabilities).

Severity (CVSS 3.1)7.8High

Exploit odds (30 days)0.4%top 63.2% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

Official description

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 products (as reported)

Vendor	Product	Versions
h5io	h5io	0.1.0 – before 0.2.6

Weakness: CWE-95, CWE-502 · Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

References

GitHub Security Advisory (GHSA-vwvw-f6v4-w737) vendor-advisory
https://github.com/h5io/h5io/commit/afff1d61b31790f8c27e6c577bb7703eb1883ddd patch
h5io h5io-0.2.6 Release Notes release-notes
https://github.com/h5io/h5io/blob/h5io-0.2.5/h5io/_h5io.py#L601-L604 technical-description
VulnCheck Advisory: h5io before 0.2.6 Arbitrary Code Execution via read_hdf5 third-party-advisory