It looks like you can still use the older odbc libraries with Oracle 12. The Oracle Services Reference mentions the SQLNET.ALLOWED_LOGON_VERSION_SERVER and SQLNET.ALLOWED_LOGON_VERSION_CLIENT parameters, which determine the minimum allowable versions allowed to connect to and from the database. Both defaults to 11, which is equivalent to Oracle Database 11g authentication protocols. Therefore, any driver for Oracle 11g clients must still work with the Oracle 12c database.
I tested this with the Java client using the ojdbc6.jar library to connect 11g to my Oracle 12c database and version 5.1.2 cx_Oracle for Python.
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