According to the documentation this should work.
SELECT SDO_GEOMETRY(HEXTORAW('0102000000030000009FD921FD6F4858C0CC4362115FF448401730C19D874858C0936C8A8B64F4484099E9623E8A4858C0495F69A652F44840')) FROM DUAL
It throws an en exception
ORA-29532: Java call terminated by uncaught Java exception: java.lang.RuntimeException: -2
ORA-06512: at "MDSYS.SDO_JAVA_STP", line 79
ORA-06512: at "MDSYS.SDO_UTIL", line 5764
ORA-06512: at "MDSYS.SDO_GEOMETRY", line 180
ORA-06512: at line 1
The strange thing is that this works.
SELECT SDO_UTIL.FROM_WKBGEOMETRY(HEXTORAW('0102000000030000009FD921FD6F4858C0CC4362115FF448401730C19D874858C0936C8A8B64F4484099E9623E8A4858C0495F69A652F44840')) FROM DUAL;
This error occurs regardless of how the query is run. I've tried Python, DataGrip, or SQLDeveloper.
Python 3.6.7
cx-Oracle 7.1.3
Oracle Instant Client 12.2.0.1.0
Oracle Database 12c Standard Edition Release 12.2.0.1.0