CRITICAL9.8
PYSEC-2026-349
H2O affected by a deserialization vulnerability
Details
A deserialization vulnerability exists in h2oai/h2o-3 versions <= 3.46.0.7, allowing attackers to read arbitrary system files and execute arbitrary code. The vulnerability arises from improper handling of JDBC connection parameters, which can be exploited by bypassing regular expression checks and using double URL encoding. This issue impacts all users of the affected versions.
Are you affected?
Enter the version of the package you're using.
Affected packages
PyPI/h2o
Introduced in:
0No fixed version published yet for h2o (pip). Pin to a known-safe version or switch to an alternative.
References
- https://nvd.nist.gov/vuln/detail/CVE-2025-6544[ADVISORY]
- https://github.com/h2oai/h2o-3/commit/0298ee348f5c73673b7b542158081e79605f5f25[WEB]
- https://github.com/h2oai/h2o-3[PACKAGE]
- https://huntr.com/bounties/53f35a0f-d644-4f82-93aa-89fe7e0aed40[WEB]
- https://pypi.org/project/h2o[PACKAGE]
- https://github.com/advisories/GHSA-5w3j-gwgh-4rfv[ADVISORY]