Starting with JDBC 10.2 drivers, having more than one JDBC jar file in the CLASSPATH may result in a java.lang.SecurityException: Sealing violation exception.
Detailed explanation from Oracle is documented in the following Oracle Document ID:
Note:405446.1 Subject: JDBC Driver 10.2 Uses Sealed JAR files and May Cause SecurityException Sealing Violation
(Suggested by Oracle) Make sure that the CLASSPATH includes only one JDBC driver JAR file.