CVE-2026-3960: h2o

Critical severity, CVSS 9.8. EPSS: 1% chance of exploitation in the next 30 days.

A critical remote code execution vulnerability exists in the unauthenticated REST API endpoint /99/ImportSQLTable in H2O-3 version 3.46.0.9 and prior. The vulnerability arises due to insufficient security controls in the parameter blacklist mechanism, which only targets MySQL JDBC driver-specific dangerous parameters. An attacker can bypass these controls by switching the JDBC URL protocol to jdbc:postgresql: and exploiting PostgreSQL JDBC driver-specific parameters such as socketFactory and socketFactoryArg. This allows unauthenticated attackers to execute arbitrary code on the H2O-3 server with the privileges of the H2O-3 process. The issue is resolved in version 3.46.0.10.

Affected products

• h2o h2o: before 3.46.0.10 (fixed in 3.46.0.10)

Published 2026-04-23. Last modified 2026-06-17.