Mandriva Linux Security Advisory 2009-306 - Dovecot 1.2.x before 1.2.8 sets 0777 permissions during creation of certain directories at installation time, which allows local users to access arbitrary user accounts by replacing the auth socket, related to the parent directories of the base_dir directory, and possibly the base_dir directory itself. The updated packages have been patched to correct these issues.
d9571c3961fd47c956899a4032f0b9a1cf3398e9d0bebaf5ba4b56b9ba832758