CVE-2025-6544
Critical
Description
A deserialization vulnerability exists in h2oai/h2o-3 versions <= 3.46.0.8, 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.
SeverityCritical
CVSS9.8
Exploit probability—
Product
H2o
PublishedSep 21, 2025
First seenSep 21, 2025
Weakness typeCWE-502Deserialization of untrusted data
How to fix
Sources list no fixed version or patch link for this vulnerability.
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| h2o h2o | 3.0.0.2 ≤ v ≤ 3.46.0.8 | — |
| ai.h2o:h2o-coreMaven | v ≤ 3.46.0.7 | — |
| h2oPyPI | v ≤ 3.46.0.7 | — |
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