Samba upgrade to version 3.6.3 fixes the following security issue:

- PIDL based autogenerated code allows overwriting beyond of allocated
array. Remove attackers could exploit that to execute arbitrary code
as root (CVE-2012-1182, bso#8815, bnc#752797)

Please see /usr/share/doc/packages/samba/WHATSNEW.txt from the
samba-doc package or the package change log (rpm -q --changelog
samba) for more details of the version update.