PT-2026-53438 · Pypi · H2O

Published 2026-06-29 · Updated 2026-06-29

OSV

CVSS v3.1

9.8

Critical

Base vector

AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

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.

Fix

Related Identifiers

PYSEC-2026-349

Affected Products

H2O

References · 7

• https://osv.dev/vulnerability/PYSEC-2026-349 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2025-6544 · Security Note
• https://github.com/h2oai/h2o-3/commit/0298ee348f5c73673b7b542158081e79605f5f25 · Note
• https://github.com/h2oai/h2o-3 · Note
• https://pypi.org/project/h2o · Note
• https://github.com/advisories/GHSA-5w3j-gwgh-4rfv · Note
• https://huntr.com/bounties/53f35a0f-d644-4f82-93aa-89fe7e0aed40 · Note