AFP Server on Mac OS X 10.3.x to 10.3.5, under certain conditions, does not properly set the guest group ID, which causes AFP to change a write-only AFP Drop Box to be read-write when the Drop Box is on a share that is mounted by a guest, which allows attackers to read the Drop Box.
http://www.securityfocus.com/bid/11322
http://lists.apple.com/archives/security-announce/2004/Oct/msg00000.html