pgpartman is a PostgreSQL extension that manages partitioned tables by time or ID. Prior to 5.5.0, runmaintenance(), showpartitions(), showpartitioninfo(), undopartition(), and partitiondatatime() interpolate the writable partconfig.timedncoder text value without identifier quoting into dynamic SQL. A role with the documented partmanuser privileges can store SQL rather than a decoder function name. When an affected operation later uses the poisoned value, including pgpartmanbgw 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.