Ubuntu Security Notice 454-1 – PostgreSQL did not handle the “search_path” configuration option in a secure way for functions declared as “SECURITY DEFINER”. Previously, an attacker could override functions and operators used by the security definer function to execute arbitrary SQL commands with the privileges of the user who created the security definer function. The updated version does not search the temporary table schema for functions and operators any more.
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/56354/USN-454-1.txt
Source: https://packetstormsecurity.com/files/56354/Ubuntu-Security-Notice-454-1.html