A flaw was discovered in postgresql versions 9.4.x before 9.4.24, 9.5.x before 9.5.19, 9.6.x before 9.6.15, 10.x before 10.10 and 11.x before 11.5 where arbitrary SQL statements can be executed given a suitable SECURITY DEFINER function. An attacker, with EXECUTE permission on the function, can execute arbitrary SQL as the owner of the function.

A vulnerability was found in PostgreSQL versions 11.x up to excluding 11.3, 10.x up to excluding 10.8, 9.6.x up to, excluding 9.6.13, 9.5.x up to, excluding 9.5.17. PostgreSQL maintains column statistics for tables. Certain statistics, such as histograms and lists of most common values, contain values taken from the column. PostgreSQL does not evaluate row security policies before consulting those statistics during query planning; an attacker can exploit this to read the most common values of certain columns. Affected columns are those for which the attacker has SELECT privilege and for which, in an ordinary query, row-level security prunes the set of rows visible to the attacker.

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’.