PostgreSQL:
pg_upgrade normally restricts its temporary files to be readable and writable only by the calling user. But the temporary file containing pg_dumpall -g output would be group- or world-readable, or even writable, if the user's umask setting allows. In typical usage on multi-user machines, the umask and/or the working directory's permissions would be tight enough to prevent problems; but there may be people using pg_upgrade in scenarios where this oversight would permit disclosure of database passwords to unfriendly eyes.