Lukasz,
> I think about a case where a CGI script saves some important
> information in a temporary file, like PHP do with the sessions:
>
> -rw------- 1 nobody nobody 329 May 14 12:16 /tmp/sess_0cd156a633
>
> When you have installed in.fingerd, and the in.fingerd is vulnerable,
> all local users are able to read the information from the files.
You should not run multiple daemons using the same 'unprivileged'
account. Nobody itself is an extreemly poor choice since the sole
intention of nobody's introduction was to map root to an unprivileged
account when accessing files over NFS.
Run your http daemon as user http (or something like that), and this
problem disappears.
Joep