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.

The PL/php add-on 1.4 and earlier for PostgreSQL does not properly protect script execution by a different SQL user identity within the same session, which allows remote authenticated users to gain privileges via crafted script code in a SECURITY DEFINER function, a related issue to CVE-2010-3433.

The postgresql-ocaml bindings 1.5.4, 1.7.0, and 1.12.1 for PostgreSQL libpq do not properly support the PQescapeStringConn function, which might allow remote attackers to leverage escaping issues involving multibyte character encodings.