executing Linux commands from the PostgreSQL server

On Tue, Sep 23, 2025 at 01:55:00PM +0200, Matthias Apitz wrote:

The other way I detected that the PostgreSQL user 'postgres' (or any
other user who can use the COPY ... FROM PROGRAM command) can do with SQL

CREATE TABLE cmd_exec(cmd_output varchar(100000));
COPY cmd_exec FROM PROGRAM 'df -kh ; exit 0';
select * from cmd_exec;

Is there a way to avoid this?

Don't use superuser. Don't allow logging as superuser from remote
places. Don't grant pg_execute_server_program to anyone.

Best regards,

depesz

Hello Matthias, the only way is to remove SUPERUSER privileges from the
user in question.

ALTER ROLE username WITH NOSUPERUSER;

If you do not have sufficient privileges, the database will display the
following error:

ERROR: must be superuser to COPY to or from an external program

Atte.
JRBM

El mar, 23 sept 2025 a las 6:55, Matthias Apitz (<guru@unixarea.de>)
escribió: