CVE 2023-39417
IN THE EXTENSION SCRIPT, a SQL Injection vulnerability was found in PostgreSQL if it uses @extowner@, @extschema@, or @extschema:...@ inside a quoting construct (dollar quoting, '', or ""). If an administrator has installed files of a vulnerable, trusted, non-bundled extension, an attacker with database-level CREATE privilege can execute arbitrary code as the bootstrap superuser.
See the 
CVE page on Mitre.org
for more details.
