CVE-2026-120499: h5io h5io

h5io before 0.2.6 Arbitrary Code Execution via read_hdf5

CVSS 8.5 High

Published by the CVE Program (CNA: VulnCheck) at 5 Nov 2026, 16:55 UTC. agentprime has not analysed this yet, so whether it affects any app is not known. This CVE names a vendor and product rather than a package, so the lockfile check doesn’t match it.

Affected products, as the CNA wrote them
Vendor	Product	Versions
h5io	h5io pkg:pypi/h5io	affected 0.1.0 to before 0.2.6 semver Other versions: unaffected

Identifiers

CVE-2026-120499

CNA

VulnCheck

Weakness (CWE)

CWE-95 · CWE-502

Not analysed yet

We haven’t published our own analysis of this CVE. If a person reviews it, this page will say what’s affected and what has to be true for it to matter.

Severity and exploitation

Score	Rating	CVSS	Vector	Source
8.5	High	4.0	CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N	CNA (VulnCheck)Used for this record
7.8	High	3.1	CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H	CNA (VulnCheck)

CISA KEV Not listed.
EPSS No score.

Timeline

5 Nov 2026, 16:55 UTC Confirmed by the CVE List
5 Nov 2026, 17:04 UTC First seen by agentprime
5 Nov 2026, 17:18 UTC Confirmed by NVD

Sources

References from the CNA

github.com/h5io/h5io/security/advisories/GHSA-vwvw-f6v4-w737 vendor-advisory
github.com/h5io/h5io/commit/afff1d61b31790f8c27e6c577bb7703eb1883ddd patch
github.com/h5io/h5io/releases/tag/h5io-0.2.6 release-notes
github.com/h5io/h5io/blob/h5io-0.2.5/h5io/_h5io.py#L601-L604 technical-description
www.vulncheck.com/advisories/h5io-before-0.2.6-arbitrary-code-execution-via-read-hdf5 third-party-advisory

Facts on this page come from the CVE List as the CNA published them, with CVSS from the sources named above, CISA KEV and FIRST EPSS. Vendors, products and versions are shown as the CNA wrote them. We don’t reproduce the CVE’s description.