RCE in H5io
CVE-2026-120499
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.8 (High). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.004 (36.9th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 37th percentile — 36.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
The 30-day trend appears once there are two daily scores.
Affected products
Weakness classification (CWE)
References
- github.com/h5io/h5io/blob/h5io-0.2.5/h5io/_h5io.py (technical-description)
- github.com/h5io/h5io/commit/afff1d61b31790f8c27e6c577bb7703eb1883ddd (patch)
- github.com/h5io/h5io/releases/tag/h5io-0.2.6 (release-notes)
- github.com/h5io/h5io/security/advisories/GHSA-vwvw-f6v4-w737 (vendor-advisory)
- www.vulncheck.com/advisories/h5io-before-0.2.6-arbitrary-code-execution-via-rea… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-120499?
- CVE-2026-120499 is a high-severity vulnerability in H5io, classified under Eval Injection. CVSS score: 7.8/10. Published 2026-11-05.
- How severe is CVE-2026-120499?
- High severity. CVSS v3 base score is 7.8 out of 10.