pg_partman privilege escalation via SQL injection in several functions via time decoder

pg_partman is a PostgreSQL extension that manages partitioned tables by time or ID. Prior to 5.5.0, run_maintenance(), show_partitions(), show_partition_info(), undo_partition(), and partition_data_time() interpolate the writable part_config.time_dncoder text value without identifier quoting into dynamic SQL. A role with the documented partman_user privileges can store SQL rather than a decoder function name. When an affected operation later uses the poisoned value, including pg_partman_bgw maintenance for a text- or UUID-keyed set, the SQL executes with the operation's privileges, which can be the default PostgreSQL superuser background-worker role. The persistent row can restore elevated access on later ticks, and successful exploitation can permit database-wide compromise and operating-system command execution as the PostgreSQL service account. This issue is fixed in version 5.5.0.