An unauthenticated REST API endpoint, /99/ImportSQLTable, in H2O-3 allows an attacker to execute arbitrary code on the server. The vulnerability stems from an insufficient blacklist that only filters MySQL JDBC driver parameters, enabling an attacker to switch the JDBC URL protocol to jdbc:postgresql: and use PostgreSQL‑specific parameters such as socketFactory and socketFactoryArg. By exploiting this loophole, an attacker can run arbitrary code with the privileges of the H2O‑3 process, potentially compromising confidentiality, integrity, and availability of the entire system.

The affected product is H2O-3 from h2oai. Versions 3.46.0.9 and any earlier release are vulnerable. The issue has been addressed in version 3.46.0.10, which eliminates the insecure parameter handling.

The CVSS score of 9.8 indicates a critical severity, while the EPSS score of <1% suggests a low probability of exploitation under current circumstances. The vulnerability is not listed in the CISA KEV catalog. Attackers are presumed to reach the endpoint over the network with no authentication required, making it a likely vector for exploitation if the API is exposed. The exploit requires only standard network traffic to the REST service and no special privileges beyond that.