The PostgreSQL project reports:
Memory disclosure in INSERT ... ON CONFLICT ... DO UPDATE
Using an INSERT ... ON CONFLICT ... DO UPDATE command on a
purpose-crafted table, an attacker can read arbitrary bytes of
server memory. In the default configuration, any authenticated
database user can create prerequisite objects and complete this
attack at will. A user lacking the CREATE and TEMPORARY privileges
on all databases and the CREATE privilege on all schemas cannot use
this attack at will..
Buffer overrun from integer overflow in array subscripting
calculations
While modifying certain SQL array values, missing bounds checks let
authenticated database users write arbitrary bytes to a wide area of
server memory.