Heap-based buffer overflow in PostgreSQL foreign batch inserts allows a foreign server to execute arbitrary code, via reporting that it inserted more rows than the server supplied. postgres_fdw can legitimately encounter this when a rule on the remote table expands an INSERT into additional rows. Versions before PostgreSQL 18.7, 17.12, 16.16, 15.20, and 14.25 are affected.
Superuser previously issued "CREATE EXTENSION postgres_fdw"; attacker has local permission to create objects (temporary objects or non-temporary objects in at least one schema); attacker has remote-server permission to create non-temporary objects in at least one schema.