PostgreSQL 10.x before 10.1, 9.6.x before 9.6.6, 9.5.x before 9.5.10, 9.4.x before 9.4.15, 9.3.x before 9.3.20, and 9.2.x before 9.2.24 runs under a non-root operating system account, and database superusers have effective ability to run arbitrary code under that system account. PostgreSQL provides a script for starting the database server during system boot. Packages of PostgreSQL for many operating systems provide their own, packager-authored startup implementations. Several implementations use a log file name that the database superuser can replace with a symbolic link. As root, they open(), chmod() and/or chown() this log file name. This often suffices for the database superuser to escalate to root privileges when root starts the server.

INSERT ... ON CONFLICT DO UPDATE commands in PostgreSQL 10.x before 10.1, 9.6.x before 9.6.6, and 9.5.x before 9.5.10 disclose table contents that the invoker lacks privilege to read. These exploits affect only tables where the attacker lacks full read access but has both INSERT and UPDATE privileges. Exploits bypass row level security policies and lack of SELECT privilege.

Invalid json_populate_recordset or jsonb_populate_recordset function calls in PostgreSQL 10.x before 10.1, 9.6.x before 9.6.6, 9.5.x before 9.5.10, 9.4.x before 9.4.15, and 9.3.x before 9.3.20 can crash the server or disclose a few bytes of server memory.

PostgreSQL versions before 9.2.22, 9.3.18, 9.4.13, 9.5.8 and 9.6.4 are vulnerable to authorization flaw allowing remote authenticated attackers to retrieve passwords from the user mappings defined by the foreign server owners without actually having the privileges to do so.

PostgreSQL versions before 9.2.22, 9.3.18, 9.4.13, 9.5.8 and 9.6.4 are vulnerable to incorrect authentication flaw allowing remote attackers to gain access to database accounts with an empty password.

PostgreSQL versions 8.4 - 9.6 are vulnerable to information leak in pg_user_mappings view which discloses foreign server passwords to any user having USAGE privilege on the associated foreign server.

In PostgreSQL 9.3.x before 9.3.17, 9.4.x before 9.4.12, 9.5.x before 9.5.7, and 9.6.x before 9.6.3, it was found that the PGREQUIRESSL environment variable was no longer enforcing a SSL/TLS connection to a PostgreSQL server. An active Man-in-the-Middle attacker could use this flaw to strip the SSL/TLS protection from a connection between a client and a server.

It was found that some selectivity estimation functions in PostgreSQL before 9.2.21, 9.3.x before 9.3.17, 9.4.x before 9.4.12, 9.5.x before 9.5.7, and 9.6.x before 9.6.3 did not check user privileges before providing information from pg_statistic, possibly leaking information. An unprivileged attacker could use this flaw to steal some information from tables they are otherwise not allowed to access.