It was found that some PostgreSQL extensions did not use search_path safely in their installation script. An attacker with sufficient privileges could use this flaw to trick an administrator into executing a specially crafted script, during the installation or update of such extension. This affects PostgreSQL versions before 12.4, before 11.9, before 10.14, before 9.6.19, and before 9.5.23.
The product searches for critical resources using an externally-supplied search path that can point to resources that are not under the product's direct control.