Postgresql: role pg_signal_backend can signal certain superuser processes.

A flaw was found in PostgreSQL involving the pg_cancel_backend role that signals background workers, including the logical replication launcher, autovacuum workers, and the autovacuum launcher. Successful exploitation requires a non-core extension with a less-resilient background worker and would affect that specific background worker only. This issue may allow a remote high privileged user to launch a denial of service (DoS) attack.