autofs includes a configuration file, /etc/auto.smb, which is intended to
be used for SMB/CIFS shares.

This confile makes use of $UID and $GID. Ordinarily in autofs these are
expanded to the UID and GID of the user who has caused a mount to be
attempted.

However, per "man 5 autofs":
       If a program map is used these standard environment variables will
have
       a prefix of "AUTOFS_" to prevent interpreted languages like python
from
       being able to load and execute arbitray code from a user home direc‐
       tory.

Since auto.smb is a program map, it should instead refer to $AUTOFS_UID
and $AUTOFS_GID.