The Apple mod_hfs_apple module for the Apache HTTP Server in Apple Mac OS X before 10.8.3 does not properly handle ignorable Unicode characters, which allows remote attackers to bypass intended directory authentication requirements via a crafted pathname in a URI.
https://euvd.enisa.europa.eu/vulnerability/EUVD-2013-0977
http://lists.apple.com/archives/security-announce/2013/Mar/msg00002.html