[c-nsp] Using "autocommand" securely?

[Seth Mattinen]

I have an old PM25 that obviously doesn't support telnet that I use for
serial console access, so I thought of using the following quick and
dirty way of giving it some external transport security via SSH to a
cisco and autocommanding to telnet:

username bettysue noescape nohangup user-maxlinks 1 password x
username bettysue autocommand telnet 1.2.3.4 5678

Is there anything bad or insecure about doing this i.e. any way to get
to the IOS prompt or to abuse the router itself?

~Seth