PostgreSQL versions 10.x before 10.9 and versions 11.x before 11.4 are vulnerable to a stack-based buffer overflow. Any authenticated user can overflow a stack-based buffer by changing the user's own password to a purpose-crafted value. This often suffices to execute arbitrary code as the PostgreSQL operating system account.
In PostgreSQL 9.3 through 11.2, the "COPY TO/FROM PROGRAM" function allows superusers and users in the 'pg_execute_server_program' group to execute arbitrary code in the context of the database's operating system user. This functionality is enabled by default and can be abused to run arbitrary operating system commands on Windows, Linux, and macOS. NOTE: Third parties claim/state this is not an issue because PostgreSQL functionality for ‘COPY TO/FROM PROGRAM’ is acting as intended. References state that in PostgreSQL, a superuser can execute commands as the server user without using the ‘COPY FROM PROGRAM’.
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.