CUPS before 1.1.21rc1 treats a Location directive in cupsd.conf as case sensitive, which allows attackers to bypass intended ACLs via a printer name containing uppercase or lowercase letters that are different from what is specified in the directive.
www.cups.org/str.php?L700
www.novell.com/linux/security/advisories/2005_18_sr.html
www.redhat.com/support/errata/RHSA-2005-571.html
www.ubuntu.com/usn/usn-185-1
bugzilla.redhat.com/bugzilla/show_bug.cgi?id=162405
bugzilla.redhat.com/bugzilla/show_bug.cgi?id=163274
oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A9940